Undertaking the flood risk sequential test

In the recent case of Gladman v Secretary of State for Homes, Communities and Local Government (1) Lancaster City Council (2) [2026] EWHC 51 (Admin), the High Court quashed an Inspector’s refusal of land promoter Gladman Developments Limited’s plans for a 644‑home scheme near Lancashire, finding that the Inspector was wrong in concluding that the promoter’s failure to carry out a flood risk sequential test constituted a “clear reason for refusing the development”. My colleague Leticia Mandra sets out her thoughts on this below.

Flood risk, appeals and PPG updates

It is worth noting that the appeal decision and High Court hearing took place before September 2025 when the updates to the Planning Practice Guidance were made. The changes brought welcome clarity and proportionality to the use of the sequential test for surface water flooding by confirming that where a site-specific flood‑risk assessment clearly shows that the layout, design and mitigation will keep future occupiers safe for the lifetime of the development - and will not increase flood risk elsewhere – the sequential test is not required. Nevertheless, this judgment shows how such issues are weighed in the overall planning balance, including in the context of appeal risk and legal challenge.

The Inspector’s decision – key facts

In dismissing the appeal by Gladman in November 2024, the Inspector in her  Decision Letter (“DL”) accepted that:

• almost the entire site was in Flood Zone 1;
• only a “very small area” fell within Flood Zones 2 and 3; and
• the proposals would deliver betterment by reducing off‑site flood risk. 

She also acknowledged that the Council’s housing land supply was only 2.4 years, and that the delivery of the new homes carried “substantial weight”. Despite this, the Inspector concluded that the absence of a sequential test was a “clear reason for refusing the development” under Footnote 7 of the NPPF, and therefore amounted to an overriding policy conflict.

High Court judgment 

Gladman challenged the DL, arguing that the Inspector had treated national policy on flood risk contained in the NPPF as establishing a requirement that planning permission must be refused in every case where a sequential test is required but not undertaken. Justice Lieven agreed and the Court held that the Inspector had treated the missing sequential test as “fatal…without carrying out any proper or meaningful balance with the development plan and NPPF, and the other material considerations.” 

Crucially, the Inspector gave no explanation for why the policy conflict outweighed the scheme’s significant benefits or why the absence of a sequential test was a clear reason for refusal. In doing so, she was found to have taken an inflexible and mechanistic approach to the policy conflict, and it was this approach which was ruled to be unlawful.

A word of caution

It is important to emphasise that neither this judgment nor recent policy updates mark the “death” of the sequential test. The Court was careful not to criticise the Inspector for requiring a sequential test, and to emphasise that the error in law lay specifically in treating its absence as automatically fatal without any proper balancing exercise.

 As such, sequential test failures may still carry significant weight and justify refusal on the facts. The judgment reinforces that decision‑makers must explain their reasoning and that simply stating that a planning balancing exercise is being carried out is not sufficient where no meaningful balancing exercise takes place.

If you have any queries regarding flood risk, please do reach out to Jen Ashwell or Leticia Mandra.