YORK Theatre Royal's £4.1 million redevelopment will sustain the future of England's longest running theatre outside London for the next 60 years, bosses say.

The theatre, in St Leonard's Place, will close for eight months from March 17 next year for the foyer space to be increased, the auditorium reconfigured and refurbished and the whole building made more accessible with north and south entrances.

A temporary 1,000-seat theatre will be created at the National Railway Museum during the closure.

The theatre will reopen with Berwick Kaler's 2015/16 pantomime, whose title is yet to decided. "It's right that the pantomime should be the first show," said artistic director Damian Cruden at today's launch.

Central to the project is Arts Council England's £2.9 million award, the most significant investment in the Theatre Royal since the 1967 foyer extension by Welsh modernist architect Patrick Gwynne.

Announcing the redevelopment, Theatre Royal chief executive Liz Wilson said: “A theatre has been operating on this site since 1744. We're immensely proud York Theatre Royal is the oldest continuously working theatre in the country outside of London, but, more so because what we have here is not a museum; it's still a thriving venue, hugely loved by the people of York and the surrounding area and integral to the healthy cultural life of this city.

"This investment allows us to take the next step in securing our future and ensuring we continue to provide the very best theatrical experiences for the next generation”.

Angus Morrogh-Ryan from the project's London architects, De Matos Ryan, today introduced the design plans, which will involve glazing the colonnade and opening up the space around the exhibition corridor to create new and more spacious welcome areas. New cafe and restaurant facilities and a new box office will be created.

The audience flow will be improved, including the reopening or the old Georgian staircase as part of creating north and south entrances.

The stalls will be reconfigured with raked seating rising to the dress circle, giving better views; the formerly raked stage will be flat, better for ballet companies and the theatre technicians; and more room will be created under the stage for more trap entrances through the stage floor.

A new foyer lift will improve access and there will be new seating for wheelchair users in the dress circle, along with flip-up seats for cheaper-priced tickets. More bars and lavatories will be added.

The project is the first phase of a ten to 15-year plan to make the Theatre Royal greener and more sustainable, while allowing it to make the best possible use of the space to maximise income and help secure its future.

The theatre needs a further £500,000 from applications to trusts and foundations, public appeals and individual donors after a £500,000 contribution from City of York Council and funding from the Garfield Weston Foundation, Liz and Terry Bramall Foundation, The Feoffees of St Michaels, Spurriergate, and Joseph Rowntree Foundation.

While closed, York Theatre Royal will link up with the National Railway Museum, as it did for The Railway Children in 2008 and 2009. Mike Kenny's adaptation will be revived in a temporary, purpose-built, 1,000-seat space in the museum grounds, and a new community play with the working title of Steamwill allow audiences to explore the NRM's collections in innovative ways.