Cancelling a series of music festivals would be a “devastating blow” that leaves tens of thousands of people “in limbo”, the Night Time Industries Association (NTIA) has warned.

A series of events, including the Mighty Hoopla, Cross The Tracks and Wide Awake, are due to be held at Brockwell Park in south London from 23 May until 8 June.

But on Friday, resident Rebekah Shaman won a High Court challenge over the use of the site this summer, after arguing that the council did not have the correct planning permission for the events.

A Lambeth Council spokesperson said: “We are currently assessing the impact of this judgment and determining next steps.”

Michael Kill, chief executive of the NTIA, said cancelling the series of festivals “would directly impact thousands of people… many of whom rely on the summer season to sustain their livelihoods”.

“The supply chain, from staging and lighting companies to local food and drink vendors, would suffer heavy financial losses,” he said.

“The local economy – including independent shops, pubs, restaurants, and hotels – which sees a surge in business during these festivals, would be hit hard.”

Solicitors acting on behalf of the Protect Brockwell Park campaign group have written a letter to Lambeth Council calling for events to be called off.

“The effect of the judgment is that the Brockwell Live event does not have planning permission,” they said.

“As there is no planning permission for the Brockwell Live event, the event has to be cancelled.

“The site now has to be made immediately available to the public and cleared of the fencing and infrastructure.”

Ms Shaman’s legal argument centred around planning laws that prohibit changing the use of a park for more than 28 days each year without additional planning consent.

Presiding over the case, Mr Justice Mould found that parts of Brockwell Park would be used for these events for as many as 37 days during the series of festivals.

The judge said his ruling was only about the lawfulness of the council’s decision to grant permission for the additional days – a decision he described as “irrational”.

Ms Shaman said she did not want to take Lambeth Council to court, but felt as though it was not engaging with residents.

“This has been going on for years, it isn’t a one-off situation and it has been a consistent deterioration of the park, to the point where the community had to speak up to protect the park for future generations,” she said.

She added: “We are hoping to come to an agreement where events can still continue, but on a much lower level and also much more connected to the community.”

Lawyers for Lambeth Council and festival organisers Summer Events Limited both asked for permission to challenge his decision but the judge refused.

However, they are still able to ask the Court of Appeal for permission to challenge the decision directly.

A spokesperson for the organisers said: “Summer Events Limited are considering the judgment concerning Brockwell Live with their legal team.

“It would not be appropriate to comment further while legal proceedings are ongoing.”