Highgate theatres have welcomed a new report calling on the Mayor of London to implement recommendations which will help increase audiences and make it easier for fringe venues to access funding.

A recent study found almost half of small theatres in the capital felt “insecure” about their financial future due to a lack of funding and the constant threat of being pushed out by developers.

As part of the investigation by the London Assembly, 55 small theatres were surveyed and 13 venues were paid a visit by members from its cross-party economy committee.

Among them were Upstairs at the Gatehouse and Jacksons Lane in Highgate. Bosses at both theatres say ticket sales are up but they have insufficient means to market their shows.

John Plews, artistic director of Upstairs at the Gatehouse and chair of the Society of Independent Theatres, said: “Some theatres are under constant threat from their landlords because very few own their buildings.

“Fortunately we have a really good relationship with Wetherspoon’s and a long lease in place, but I know a lot of others are short-term and the freehold is constantly changing and that’s where the inconsistency comes from.”

He said ticket sales at the Gatehouse had increased over the last few months, with the first fringe production of hit West End show Avenue Q helping to break box office records.

“It’s about choosing the right shows that will have commercial appeal,” Mr Plews added.

“But marketing and advertising are areas where all small theatres could do with a helping hand and we will be lobbying for reduced or free advertising space on local London Underground stations.”

Recommendations put forward by the Centre Stage report include better marketing and promotion, setting up a new fund through donations to pay for theatre repairs and access to performance space in larger theatres or vacant offices.

Jacksons Lane Arts Centre receives funding from Haringey Council and the Arts Council, but a 12 per cent increase in audience numbers since 2011 has also helped it become financially sustainable.

Chief executive James Tilston said: “Jacksons Lane was delighted to meet with the London Assembly to discuss the challenges facing theatres in London, and we welcome their report and their suggestions for ways in which they can support the development and continued success of the capital’s diverse arts scene.

“At Jacksons Lane we are particularly supportive of the suggestion that Transport for London provide free advertising space for small theatres which would create a real boost for the sector.

“The scale of cuts that have affected the Arts Council and local government have been well documented, and the work being done by our theatres in our communities is immense – both socially and culturally, as well as in terms of bringing new revenue into our local areas to support local businesses.”

Two Camden pub theatres - The Lion and Unicorn Theatre, in Kentish Town, and Etcetera Theatre, in Camden Town - were also consulted as part of the Centre Stage report.

George Sallis, artistic director of the Lion and Unicorn Theatre, said: “We’re lucky because we have a really supportive lease holder who has kept the rents down, but a lot of big pub chains want those buildings because that space can be sold or rented at a premium and that’s where local government can step in and make sure those places aren’t lost.

“It also helps we’re the only theatre in Kentish Town and we put on an eclectic programme which pulls in people from outside, whereas others might specialise in one area, such as musicals.

“The only battle we have is when people come and say ‘We didn’t know about you until now’.”