Five years ago Shaw man-agement leased the 500-seat theatre from Camden after rate-capping forced the council to cut arts grants. The theatre has broken even since then.
Last year the council, which owns the building's freehold, decided to market the site. It has been bought by Indegree Ltd, and theatre staff have been told to vacate the building by September 1.
Simon Thomsett, the Shaw's manager and artistic director, said Camden's decision had appalled the theatre's 23 staff.
'People have been working 80-hour weeks for very little money to keep this place going. The overheads for a venue like this are enormous but we have succeeded here. Most people would consider that to be a quite an achievement,' he said.
Camden has no commitment to this particular resource. Their only consideration is to ensure that the building is sold.
'The Shaw has had a troubled history, but it is so close to being more than viable. It is easy to close a theatre but much harder to open one.'
Mr Thomsett added that although he would negotiate with the new owners for permission to keep the Shaw open, he had little hope of success.
'We have seen and heard enough to know that they have no interest in maintaining it as a theatre,' he said.
Shaw management offered to buy the block's three lowest floors which house the theatre, leaving Camden to sell the rest of the building, currently occupied by advertising company CDP. However, the council rejected this, deciding the building should be sold as a single unit. Attempts to lease back the Shaw after August so that existing bookings could be honoured broke down last week, leaving several productions searching for alternative venues. Stella Sharman, chairwoman of Lloyd's Dramatic Operatic and Musical Society, which had planned to stage Kiss Me Kate at the Shaw in Nov-ember, said the move now left her only a short time to find a new auditorium.
'We have to find somewhere else because we are hoping to raise several thousand pounds for charity with the show,' she said. A spokeswoman for Camden Council said the Euston Road building had been sold as it was surplus to requirements and expensive to maintain.
'St Pancras library has been moved to the council's headquarters nearby, while office staff formerly based there have also been relocated.
'We have an obligation to get the best possible consideration for our properties.
'It is up to the Shaw Theatre management to liaise with the new owners about their future. The authority gives substantial grants to other arts organisations in the borough.'
The Shaw was opened by Camden in 1971. Appearances there helped launch the careers of comedian Eddie Izzard and singers Tori Amos and Beverley Craven.
Recent productions have included an adaptation of Isabel Allende's House of the Spirits, and Malcolm Taylor's production of Dylan Thomas's Under Milk Wood. On Sunday, comedian Jo Brand headlines The Really Quite Amusing Comedy Benefit in aid of Mencap.