The unfortunate hiatus in the progress of the Environment Bill though Parliament does, at least, provide an opportunity for reflection on the contents of the document.

The Bill touches the development control aspects of town and country planning in a number of ways, of which one is the promise of measurable biodiversity net gain as a statutory pre-condition to the carrying out of developments which will have impacts on ecology.  This seems laudable; however, it is arguable that the Bill not only does not deliver what it appears to promise, but also uses a device which is not only inelegant but also at odds with the development control process itself. 

Accordingly, this article sets out to explore:

  • whether the Bill actually promotes biodiversity net gain;
  •  whether the mechanisms in the Bill pay due regard to the established methodologies of development control; and
  • whether primary legislation is needed at all.

It concludes by suggesting that the answer to all three points is in the negative.  To put it another way, there is nothing standing in the way of the Government in implementing a deliverable regime for biodiversity net gain now, rather than await long delayed primary legislation.

 The statutory condition

Whilst the Bill contains a number of detailed provisions relating to biodiversity, this article relates to a proposed statutory pre-commencement condition.

 The Bill proposes to make provision for grants of planning permission in England to be subject to a condition to secure that the ‘Biodiversity Gain Objective’ is met.  The Biodiversity Gain Objective is met if the ‘biodiversity value attributable to the development’ exceeds the ‘pre-development biodiversity value’ of the on-site habitat by at least the “relevant percentage”.  The relevant percentage is, initially, set at 10%.[1] 

 In its current form the draft condition provides that the development may not be begun unless:

(a) a “Biodiversity Gain Plan” has been submitted to the planning authority and
(b) the planning authority has approved the plan.

 The Biodiversity Gain Plan must comply with the ‘Biodiversity Gain Objective’, thus one of the objectives of the Biodiversity Management Plan is to deliver a purported to 10 % net gain in biodiversity as a result of the development.  Unfortunately, this labelling does not match the proposed mechanisms for the simple reason that they are not designed to provide a measurable net gain in biodiversity as a whole.  The statutory condition addresses one aspect of biodiversity only.  That is to say, it is focused upon habitats alone and does not seek to address the species which will inhabit those habitats.


The Biodiversity Metric

The measure of net gain is to be by way of the application of a metric.  This poses a dilemma, because the notion of measurable net gains for biodiversity is, in theory, an attempt to invoke the measurement of that which is inherently immeasurable.  It puts one in the position of having to trying to measure the immeasurable[2].

The Biodiversity Metric 2.0 uses habitat features as a proxy measure for capturing the value and importance of nature, and comes with a free calculation tool designed to simplify and speed-up the calculation process.  It is, currently, a system, or methodology, comprising a software programme, in the form of a spreadsheet, and support documents.  They include:

·         Biodiversity Metric 2.0: Calculation tool (spreadsheet) – updated December 2019.

·         Biodiversity Metric 2.0: User guide.

·         Biodiversity Metric 2.0: Technical supplement (which includes habitat condition assessments).

·         Biodiversity Metric 2.0: Intertidal habitats guidance – beta test (published December 2019).

·         Biodiversity Metric 2.0: Connectivity Tool Guidance (published December 2019).

·         Reference Habitat Folder – for use with the Biodiversity Metric Connectivity Tool (published December 2019).


The current version of the chosen metric is the ‘Biodiversity Metric 2.0’.  This was published as a 'beta test’ version to enable wider user feedback and is, at the moment, the final draft of the Metric.  It is anticipated that the final version will be available in during 2021 and will, then, be called the ‘Biodiversity Metric 3.0’.

The Metric does not attempt to weigh the species richness[3], abundance[4] or diversity[5] of various species on the subject land.  It is not a precise measurement of all that exists on the land.

 The User Guide for Biodiversity Metric 2.0 [6] states:

1.5.. . .   . . It is important to note that achieving gains in biodiversity from the calculation does not necessarily mean a development meets any wider requirements of planning policy or law relating to nature conservation or biodiversity.[7]
2.20. The metric is a tool that can be used to help inform plans and decisions.  Used properly, it incentivises actions that are expected to benefit biodiversity and discourages actions that harm biodiversity.  It is important, however, to be aware of its limitations and to follow some important principles.

As to the important ‘proxy’ approach in the Metric, the User Guide states:

2.21. The metric uses habitat categories as a proxy for biodiversity.  Although this is rational, it is an oversimplification of the real world. Furthermore, while the scoring of habitats is informed by ecological reasoning and the available evidence, the outputs of biodiversity unit calculations are not scientifically precise or absolute values.  The generated biodiversity unit scores are proxies for the relative biodiversity worth for the state of a place.

It is necessary to gain an understanding of the net gain which is calculated by way of the Metric.  The starting point is that the Metric is based on an assessment of the ecological qualities of the habitats which may be affected by the development proposals.  Each habitat type which will be affected by the proposed development will be weighted according to established qualitative criteria on the basis that this habitat selection and weighting process will act as a proxy for biodiversity as a whole.  This is, at first brush, a pragmatic approach.  The quantum and quality of habitats is one of the main drivers of biodiversity and so one can understand the reasoning.  The adoption of a rude proxy is better than doing nothing on the basis that it is less than perfect. [8]

 Unfortunately, if adopted wholesale, then it is not an approach which is consistent with the way in which the ecological impacts of proposed development are identifies and evaluated during the development control process.  This is due to the fact that the assessments of projected impacts on species are part and parcel of this process and, indeed, have been for a long time.  Ergo, one can readily ask whether the proposed statutory pre-condition forms part of an integrated approach and whether it meshes with that which already exists ?  Arguably, it does not and, worse, it is an ungainly and troublesome accretion.  

 The Metric sets out a set of key principles for its use and ‘Principle 1’ provides that:

The Metric does not change the protection afforded to biodiversity. Existing levels of protection afforded to protected species and to habitats are not changed by use of this or any other metric.  Statutory obligations will still need to be satisfied.

Take, for example, the Habitats Regulations.  They are focussed on both species and habitats.  If the proposed development has the potential to affect certain types of habitat site, then, the developer might be required to carry out a Habitats Regulations Assessment (HRA).  Such an assessment might be required where a nearby area is designated as a European site or a European Offshore Marine Site.  If the proposed plan or project is considered likely to have a significant effect on such a protected habitat site (either individually or in combination with other plans or projects) then an Appropriate Assessment must be carried out.  This process is required by and regulated by the Conservation of Habitats and Species Regulations 2017. 

 Then there is the matter of protected plant and animal species by way of legislation which includes the Wildlife & Countryside Act 1981, the Conservation of Habitats and Species Regulations 2010 and the Protection of Badgers Act 1992.  Protected species include all species of bats, great crested newts, hazel or common dormice, otters, natterjack toads, reptiles (some species), protected plants (some species), large blue butterfly and sturgeon.  The possible impact of a proposed development on protected species is, of course, a material planning consideration.

 If one takes these cognate ecological considerations into account (as one must), then a focus on habitats only is not enough to cover the whole range of considerations relating to biodiversity.

 This does not mean that the Biodiversity Metric is otiose (far from it); however, it is (as it acknowledges) simply one tool in the overall assessment of is the impacts of the proposed development on the ecology.  Indeed, it might be more realistic (and honest) to relabel the Biodiversity Metric as the “Habitat Metric” and, instead of describing its outputs as “biodiversity units” to describe those outputs in terms of their real content.  This is to say, they are “habitat units” and not “biodiversity units”.

 Landscape and Ecological Management Plans

 Landscape and Ecological Management Plans (also referred to as a Habitat or Biodiversity Management Plans) are, now, familiar because they are mentioned in BS42020, which helpfully provides a model pre-commencement condition which may be utilised when a local planning authority is minded to seek security in ecological matters.

 It might be helpful to set out the model condition here:

 D.4.5 Landscape and ecological management plans (LEMPs) – Condition
A landscape and ecological management plan (LEMP) shall be submitted to, and be approved in writing by, the local planning authority prior [… to the commencement or occupation …] of the development [or specified phase of development]. The content of the LEMP shall include the following.
a) Description and evaluation of features to be managed.
b) Ecological trends and constraints on site that might influence management.
c) Aims and objectives of management.
d) Appropriate management options for achieving aims and objectives.
e) Prescriptions for management actions.
f) Preparation of a work schedule (including an annual work plan capable
of being rolled forward over a five-year period).
g) Details of the body or organization responsible for implementation of the plan.
h) Ongoing monitoring and remedial measures.
 The LEMP shall also include details of the legal and funding mechanism(s) by which the long-term implementation of the plan will be secured by the developer with the management body(ies) responsible for its delivery.
 The plan shall also set out (where the results from monitoring show that conservation aims and objectives of the LEMP are not being met) how contingencies and/or remedial action will be identified, agreed and implemented so that the development still delivers the fully functioning biodiversity objectives of the originally approved scheme.
The approved plan will be implemented in accordance with the approved details.

 Item c) refers to the “aims and objectives of management.  BS42020 was drafted before the Biodiversity Metric took shape and so it is worth adding that the condition could be modified by providing that one of the objectives of the LEMP would be to achieve a specified net increase in habitat units in accordance with calculations pursuant to the Metric.  Thus, the Metric is readily absorbed into the pre-existing framework.  

It is necessary to take an holistic approach because the features of many modern developments serve more than one purpose.  Thus, greenspace SUDS mechanisms (such as balancing ponds) may count as habitat for the purposes of the Metric.  Likewise, roadside verges, vegetated roundabouts, service margins and amenity strips.  These areas should be maintained for their base purposes but also for their contributions to net gain.  The provision of SANGS might be necessary to meet the Habitat Regulations and, again, the LEMP should make provision for them.  None of this is new, therefore it is difficult to see the contribution to be made by a statutory Biodiversity Management Plan beyond the fact that it statutory - and this opens to the next point. 

 Planning obligations have evolved to include complex and interdependent provisions which may range across the development proposals as whole.  For example, a phasing plan may have ramifications for the staged delivery of the measures required of the developer.  Thus, taking greenspace as an example, it might be important to tie its delivery to particular phases in a development.  This may, in turn, have implications for the delivery of other infrastructure or visa versa. If this is the case for a major scheme, then it might be prudent to deal with these matters by way of a planning obligation rather than conditions.  Other than being a troublesome and duplicating side issue, it is difficult to see how a pre-commencement condition will assist or mesh with this approach.  The condition will operate according to the regime which governs conditions in parallel with the regime which governs planning obligations when the objective of the exercise is to provide a coherent holistic approach to these matters.

 The need for primary legislation?

 Arguably, the objectives of the statutory pre-condition can be met without the need for primary legislation by using, instead, the Town and Country Planning (Development Management Procedure) (England) Order 2015. 

 There is no impediment to adding a requirement that a developer must provide a draft LEMP with his application documents.  There is nothing novel in this because, of course, the Article 9 provides something similar in concept with most proposals for large schemes, in the requirement to submit Design and Access Statements.  These statements will be material considerations in the assessment of proposals and should assist in formulating the development envelope which the committee will then consider.

 Nor is this onerous because the developer should have all the relevant information to hand at this point in any event.  If the Habitat Regulations apply, then an Appropriate Assessment must be submitted, along with proposals for any required mitigation.  If the site is habitat to protected species, then, again, the information must be to hand.  Likewise, any local planning authority which is up to date in ecological matters should ask for a calculation of habitat losses and gains by way of the Biodiversity Metric. 

It might be argued that there is an important policy reason for preferring primary legislation; namely, that the costs of achieving measurable biodiversity net gain will be considerable and that, therefore, it is only proper that these should be imposed by Parliament as a whole as opposed to the exercise of an Executive fiat by way of secondary legislation.[9]  Given that the National Planning Policy Framework regularly imposes requirements which will have massive financial and logistical impacts on the development industry, one could wonder if this is a weighty objection.


The present problem is not the prejudicing the achievable in the hope of some marginal added value from the perfect, but that the approach chosen for the Bill is a partial one which does not seem to pay heed to its integration into the existing development control process.  Not only this, but it appears to be an exercise in ‘badge engineering’ which, presumably, is intended to lend weight to what the Government has called a ‘flagship Bill’.

 As is often the case, there is more than one way of skinning the unhappy metaphorical cat.  Arguably, the provisions in the Bill are too simplistic and do not lend themselves to ready integration with the existing development control framework.  But, perhaps, the cardinal point is that the objective of achieving biodiversity net gain out of the development process does not have to await this long-awaited Bill and can be achieved by way of secondary legislation and national policy.



[1] However, the Secretary of State may change the relevant percentage. 

[2]    For example, does a bee have more value than a wasp, or visa versa ?  This is not as easy a task at it might first seem.

[3]     Species richness is a measure of the number of species present at a site.  Sites with more species are considered richer. 

[4]     Species abundance and density is the total abundance and concentration of individuals present in a selected area.

[5]     Species diversity is a measure of how many different types of species are present in communities.

[6]     “The Biodiversity Metric 2.0 - auditing and accounting for biodiversity- USER GUIDE- Beta Version” Natural England Joint Publication JP029 First published 29th July 2019.

[7]     The Biodiversity Metric 2.0 - 29th July 2019

[8] Voltaire is said to have said : “Le mieux est l’ennemi du bien.” (perfect is the enemy of the good). Meaning that the costs of delaying otherwise beneficial actions (the “good”) in pursuit of the perfect solution (the “enemy”) often outweigh the marginal benefits of a metaphysical but polished perfection. There is, also, the ‘Pareto Principle’ about diminishing returns: namely, that 80% of results can be obtained with 20% of the effort.

[9] This argument could be supported by references to the Bill of Rights 1688-89 and an appeal to the Sovereignty of Parliament in such matters.  Be that as it may, the commercial and economic ramifications of this argument are far from clear because the developer will bear these costs only if he is the landowner as well, and even then, it might be that they will be reflected in projected increases in the anticipated sales revenues from the development. Otherwise, if sales prices are inflexible, they will bear on land prices. The counter-argument is that incumbent ministers and Parliamentarians do not seem to ponder such esoteric points in practice.


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