A British local council must consider the full impact of developing new drilling wells, in what could become a landmark case.

The case was brought against Surrey County Council, southern England, by local resident Sarah Finch, on behalf of campaigners.

She challenged an earlier Court of Appeal ruling dismissing her case, and emerged victorious on Friday.

According to several local news sources, the UK’s Supreme Court concluded that the environmental impact of emissions from burning fossil fuels must be considered in planning applications for new projects.

This a departure from previous guidance, which required an assessment of the impacts of the emissions produced in extracting fossil fuels, such as building wells and related infrastructure.

The assumption has always been that only the impacts from constructing the wells should be considered.

The case, which has taken several years to resolve, hinged around an oil drilling project at Horse Hill, Surrey, granted planning permission by the council in 2019.

The council said it believed it had followed planning law and had done nothing wrong.

Also, the court did not rule that the council should reject the proposal for new oil wells.

However, the judges – voting three to two in favour of allowing her appeal – argued the council should have considered the downstream emissions.

The implications of the ruling will now have to be considered by companies looking to develop new energy projects.

Finch said she was “absolutely over the moon to have won this important case”, while speaking to reporters in London.

Horse Hill oil well in Surrey was given planning permission to expand its operations in 2019, a decision that was challenged by Finch, on behalf of Weald Action Group, an umbrella organisation campaigning against all forms of extreme extraction from the Weald and the Isle of Wight.

The Surrey Weald lies to the south of London, stretching into neighbouring counties East Sussex, West Sussex, Kent, and Hampshire, and already has a small but long-standing history of oil and gas production.

According to a UK Government assessment from 2013, there could be shale oil resources of up to 4.4 billion barrels of oil in the region.

Summing up the case, Lord Leggatt said it was “inevitable” that oil from the site will be burned, and the resulting greenhouse emissions were “straightforwardly results of the project”, which should be considered.

The six wells at Horse Hill are expected to produce more than three million tonnes of crude oil over the next 20 years.

In response, Stephen Sanderson, head of UK Oil and Gas, the company behind Horse Hill, said the ruling was "perplexing", while adding that the company's focus over the past few years “has shifted away from oil and gas and firmly towards hydrogen storage”.

UK Oil and Gas PLC said it will now work with the council to amend its planning application.

The Weald Action Group said on Friday that “today’s groundbreaking ruling is a heavy blow for fossil fuel lobbyists, and the UK is already veering dangerously off track for meeting its legally binding carbon reduction targets”.