971: What does the Hillside judgment mean for infrastructure projects?

Today’s entry discusses the Supreme Court’s judgment in the Hillside Parks Ltd v Snowdonia National Park Authority case, and provides a snapshot history of overlapping DCOs.

Long live Pilkington

The Hillside judgment contains the full facts but can briefly be summarised as follows. In 1967, a planning permission for 401 homes was granted. That planning permission had incorporated within it a Master Plan. Following that permission, further permissions were sought for the land and 41 homes were constructed under those latter permissions (none of them in accordance with the 1967 Master Plan).

The developer sought to rely on the 1967 planning permission to construct further homes on the site. The local planning authority, Snowdonia National Park Authority, resisted and said that the developer could not now implement the 1967 permission given that it was not physically possible to build the development in a manner consistent with the Master Plan. The physical impossibility arose because of the development carried out under the post-1967 planning permissions. To cut a long story short, the Supreme Court agreed with Snowdonia National Park Authority.

The starting position is that you can seek overlapping and, indeed, inconsistent planning permissions over the same site. However, the implementation of such permissions is subject to the principle established in Pilkington v Secretary of State for the Environment [1973] 1 WLR 1527. The principle is that, where development has taken place under one permission, whether another planning permission may lawfully be implemented depends upon whether it remains physically possible to carry out the development authorised by the second permission in light of what has already been done under the first permission. That principle is subject to any ‘clear express provision’ making the earlier planning permission severable in some respect.

The Supreme Court has added an additional gloss on this principle holding that the, ‘Pilkington principle should not be pressed too far’ and that the ordinary presumption must be that a departure from an earlier permission under a later permission will only have the effect of neutering reliance on the earlier one ‘only if it is material in the context of the scheme as a whole’. What does material mean? Answers on a postcard.

The Supreme Court interestingly also rejected an argument that variations to part of a site should be dealt with narrowly and instead suggested that,

‘there is no reason why an approved development scheme cannot be modified by an appropriately framed additional planning permission which covers the whole site and includes the necessary modifications. The position then would be that the developer has two permissions in relation to the whole site, with different terms, and is entitled to proceed under the second.’

By the by, this seems problematic: what if the ‘development as a whole’ is EIA development, would there need to be a fresh environmental assessment? What if local planning policy has changed more generally?

How is this relevant in the infrastructure context?

This is potentially relevant in four infrastructure contexts.

First, DCOs which overlap with other DCOs. There is, as far as I am aware, only one DCO which substantively changes the works authorised under an earlier DCO under a latter DCO: the A19 / A184 Testo’s Development Consent Order 2018 is amended by the A19 Downhill Lane Development Consent Order 2020 (this wasn’t a hostile act – a friendly law firm acted for the same promoter on both)! Importantly, this does not engage the Pilkington principle in the same way because the 2020 Order amends the 2018 Order so there is, in fact, no conflict between the two. The ability to modify the initial permission in the DCO context is based on the specific power in section 120 of the Planning Act 2008.

The second context is where DCOs overlap with related planning permissions. This is now well trodden ground: the Hinkley Point C Nuclear Power Station DCO, the Riverside Energy Park DCO and the South Humber Energy Bank DCO, to name a few, all make provision relating to planning permissions for works on the same site / development or works associated with delivering an aspect of the projects earlier than the making of the DCO. This is unlikely to engage the Pilkington principle because the DCOs provisions invariably create a clean break between the relevant permissions (eg, by service of a notice so that the DCO ‘takes over’ from the earlier planning permission; or disapplies the conditions in toto).

The third context is associated development authorised under a DCO which is then modified under a planning permission. This is not uncommon but I am not going to single out any one of the 20 or so examples of this that I am aware of – but does this have the potential to engage the Pilkington principle? Perhaps, though it’s worth noting that DCOs include heavily precedented provisions which would properly regulate such matters and avoid enforcement action being taken. DCOs may need to consider additional drafting to prevent the implementation of a later planning permission invalidating the rest of the DCO if it was not fully built by then.

The fourth context is where a DCO overlaps with unrelated, third party planning permissions which have conditions or development that conflict with works authorised by a DCO. If a condition, for example, in a planning permission said that a building had to be in Area A (made up of a larger permission for Areas A to Z), and a DCO came along to move the building to some other area, is the developer of the planning permission caught by Pilkington / Hillside and prevented from completing development in Areas B to Z (if not commenced)? Well, it would depend on whether the planning permission could be construed as being severable under the terms of the planning permission but the need for severability may not have been known at the point the planning permission was made. One potential solution might be to replicate article three (3) of the Lake Lothing (Lowestoft) Third Crossing Order 2020 in DCOs where a physical inconsistency is known or likely.

Other overlaps

Speaking of overlaps, it is a useful time to mention other overlaps between DCO projects. The first example I am aware of goes back to the Galloper Wind Farm 2013 – hidden away in the protective provisions in part two of schedule six are protections for the Sizewell C Nuclear Power Station (itself granted development consent nine years later in 2022).

There is also an interesting overlap between the North London Heat and Power Generating Station Order 2017 and the National Grid (North London Reinforcement Project) Order 2014. The later DCO contains a power (in article twelve (6)) to suspend a public right of way (laid out in that order) where it may be necessary for the purposes of the earlier DCO.

We mentioned the A19 DCOs above, but there have been two (or four, depending on how you are counting) other DCOs amending other DCOs for the purposes of incorporating protective provisions in an earlier DCO. In that family are the Milbrook Power DCO which amends the Rookery South DCO, and the Immingham Gas Cycle Order which amends the Able Marine Energy Park DCO. The development in question here is unaffected so it unlikely to cause a ‘physical incompatibility’ which is the subject of the Hillside judgment.

The Thurrock Flexible Generation Plant DCO (also granted in 2022) contains protections for the Lower Thames Crossing. I do have to mention that the Lower Thames Crossing DCO application was submitted on 31 October 2022; it’s a flagship project made up of highway, overhead line and gas pipelines NSIPs – but we will not be commenting on it for obvious reasons. A decision is due by 28 November 2022.

There are a few other overlaps in the works which we are working on, but we will comment on them in our future blogs, when the relevant decisions are made!