A comprehensive survey of London’s theatre industry has found that Camden has the most vibrant fringe scene in the capital – while also shining a spotlight on widespread pay deprivation in the sector.

Off-West End productions in Camden are thriving, with the borough playing host to 10 fringe theatre venues, the highest number of any inner London borough.

But the London Theatre Report, commissioned by The Society of London Theatre and the National Theatre, also reveals the extent of the pay squeeze in the sector.

Only around one in five performers working in fringe theatre are being paid the National Minimum Wage or higher and the report found the vast majority of “low or no paid” work is taking place on the fringe.

John Plews, artistic director of Upstairs at the Gatehouse theatre in Highgate Village, said: “Unfortunately this is a huge subject which has been brewing away for the past four or five years.”

Mr Plews, who is the chairman of the Society of Independent Theatres and has sat on Equity actors’ union working party on low pay, said the issue was “high on the agenda”.

The London Theatre Report, published in July, attempted to compile a definitive list of professional London theatres for the first time and present a complete picture of the “size and shape of London theatre”.

It found that around a third, 33.5 per cent, of actors are being paid nothing at all, with nearly half, 46 per cent, being paid something but less than the National Minimum Wage.

Ten of Camden’s 25 theatres are fringe venues, including London’s smallest pub theatre the Lord Stanley in Camden Town with 30 seats, Hampstead’s Pentameters Theatre in Heath Street, and Lauderdale House in Highgate.

Addressing the issue of low pay is widely acknowledged to be a complex balancing act.

The Stage editor Alistair Smith, who authored the report, says in his introduction: “The employment chapter of this report most certainly throws up the spectre of low pay or no pay work within the London fringe sector.

“The vast majority of roles within the sector are not being paid National Minimum Wage, revealing that as well as subsidy from the government, at the bottom end, the London theatre sector as a whole is being subsidised by people giving up their time for little or no pay.”

He says the data, “makes sense bearing in mind the amount of ‘expenses only’ or ‘profit share’ working taking place on the fringe”.

The current status quo can leave actors exposed to unscrupulous operators, but it is likely that tougher regulations on pay would have a dampening effect on the number of fringe productions produced.

Lauderdale House director Katherine Ives, who is also a board member of Above The Stag fringe theatre in Vauxhall, said: “It’s a real challenge to make theatre on the fringe that is of a reasonable quality that even breaks-even, even when you’re paying everybody a minimal wage.

“It’s incredibly important that anybody producing on the fringe is up front with the actors and is absolutely fair and transparent.

“Some people do use profit share and are really open about it and then there are other people that are not necessarily as fair as they might be, which is where the problems come in.

“But if you had to pay everybody minimum wage I think the amount of fringe theatre would probably halve.

“It’s not morally right, but we’re in a climate where subsidies for creative venues are very minimal.

“Even if you sell out a show on the fringe, the venues are very small and the ticket prices are not high, there’s not much money there to be made.”

The report found that between them Camden and Westminster – the boroughs covering the heart of London’s commercial theatre sector in the West End – account for more than half of all theatre capacity in London with nearly 56,000 seats across 78 theatres.

In 2011-12 Camden box office receipts totalled £74million, rising to £87million in 2012-13, while audiences also increased from two to three million over the same period.

Camden made up 14 per cent of London’s total theatre box office receipts for 2012-13.