A kickboxing club is worried children it works with will end up "back in trouble" after it was forced to leave its premises of 44 years in Forest Gate.
Mantis has been based at Durning Hall Community Centre since 1980 but has recently had to leave due to the planned demolition of the building.
It was here that actor Idris Elba learnt the fundamentals of martial arts before filming the TV series Idris Elba: Fighter.
The site has been bought by developers and is set to be knocked down.
Mantis say they were given a three-week notice to leave.
Sabrina Mir, the club's secretary, said: "We knew that Durning Hall was set to be demolished but we weren't expecting to have to vacate so fast.
"It was very sudden. It's heartbreaking.
"A lot of our students are local children and vulnerable youths, most of whom have looked at Mantis as a safe haven.
"It really is a shame that we're losing what they considered to be a second home for so many years."
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Another staff member told The Recorder about the impact that the club has had on the Forest Gate community.
"We have spent years taking kids off the street, keeping them out of trouble and allowing them to spend their time positively.
"We see kids get into trouble and we want to stop that and encourage them to do something better, such as kickboxing.
"Not only that, but we have created British and European champions.
"We are gutted about having to leave Durning Hall. It could even result in putting kids back onto the street and back into trouble."
The club is temporarily operating from the Aston-Mansfield Community Centre in Manor Park, although it says this is not suitable for the long-term because of a lack of facilities.
Aston-Mansfield, the previous owners of Durning Hall, said: "The Durning Hall site has been sold to developers, who have told us that they will redevelop the site in line with the current planning permission.
"Despite the support of the community over the years, there are longstanding issues with the existing buildings that need to be addressed.
"Without significant work, the site was financially unsustainable and could not support us continuing our charitable work across Newham.
"The sale of the site has secured the future of Aston-Mansfield in Newham. It will allow us to develop the work that the charity does to support children, young people and families in the borough.
"Closing Durning Hall has inevitably been difficult for all of those affected.
"We have supported the Mantis Kickboxing Club to find an alternative location, and are very pleased to welcome them to the Aston-Mansfield Community Centre in Manor Park."
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