PLANS for Berwick Kaler’s 37th writing and starring role in Christmas pantomime Dick Whittington (and his Meerkat) at York Theatre Royal have had to be abandoned following the important find of a medieval hospital foundations beneath the venue during its £4m redevelopment.

The panto will now be staged at the 1,000-seat purpose-built theatre at York's National Railway Museum.

The tight 27-week schedule always had a back-up plan, and archaeologists and builders are working extended hours to complete necessary work. Over the last few weeks the archaeological finds under the stage and in the auditorium have been staggering and bigger than previously predicted.

It was previously thought that the Victorians destroyed the foundations of St Leonard’s Hospital (one of the largest and most important hospitals in medieval England) when building the theatre on the site. Last week these foundations have been uncovered. They are still intact and located underneath the stalls.

The City of York archaeologist has confirmed further excavation is needed. A longer time-frame has now been set to excavate an area of the stalls floor. Architects, De Matos Ryan, are now working on ideas for incorporating the archaeology into the new design of the theatre.

Ben Reeves chief archaeologist on the site said: "It is amazing that, considering all the alterations to the theatre since 1764, so much of the medieval hospital has survived under the stalls and elsewhere within the building. The remains are an exciting and important discovery for both archaeologists and the public, offering an opportunity to investigate and understand more about one of the city’s most fascinating and little understood sites."

A total of 13,500 people have already bought pantomime tickets. All will receive a personally addressed letter explaining the situation and being asked to trust Box Office staff to ensure they are transferred to a seat of the same value and quality in the Signal Box Theatre. Ticket sales have been suspended for a few days until current customers have been moved to the new venue.

The UK’s longest running dame, Berwick Kaler said about the switch of venue; "Artistic Director Damian Cruden has gone to great lengths to try and get rid of me but his latest effort is quite ingenious. However the laugh is on him because I have found a substitute theatre just a couple of hundred yards away from my beloved Theatre Royal – the one thousand seat NRM’s Signal Box Theatre. So while Cruden is looking for his ancestors below ground, me and ‘me bairns’ will be enjoying Dick Whittington and his Meerkat which promises to be a one-off hilarious and unique experience."

The Signal Box Theatre, a semi-permanent auditorium shipped from Toronto, is also hosting the York Theatre Royal, National Railway Museum and Pilot Theatre production In Fog and Falling Snow with George Costigan in the lead role, and the award-winning The Railway Children. The theatre is also delighted to announce that joining The Railway Children team, which includes Martin Barrass as Mr Perks, will be Berwick Kaler as the Old Gentleman.

Paul Kirkman, chief executive at the National Railway Museum, said: "With free entry to our museum, audiences will also be able to steep themselves in the spirit of Christmas past through a collection spanning more than 300 years of social history. With all this to enjoy under one roof, plus lots of available car parking, and some die-hard panto aficionados amongst our own staff, it will certainly be the season to be jolly here at the National Railway Museum."

Liz Wilson, chief executive of York Theatre Royal said; "Whilst capacity has increased by moving location, other costs have also risen. Running a temporary theatre space means there are new overheads to consider, and York Theatre Royal will also need to continue to pay for the extension of work at its regular site. The panto run will also be shortened from seven to six weeks, to cope with the extra capacity per performance, and also to ensure the re-opening of the theatre’s auditorium for early spring productions. Prior to this the theatre’s café and bar area, which has also undergone a major transformation, will open in the New Year.

The original closure period gave building landlords York Conservation Trust a limited opportunity to carry out much needed work to the external fabric of the building. Now the extension to development work gives further opportunity to complete work to additional areas not included in the original plans, such as the dressing rooms.

Philip Thake, chief executive of the trust, said: "Recent discoveries by York Archaeological Trust further confirm the importance of this historic site, and our responsibility to look after the Grade II listed building. Whilst we understand the delay will come as a surprise for theatre-goers we are also pleased that the archaeological work can continue, and that this allows us to make further improvements to the building for York Theatre Royal staff and to ensure its sustainability into the future."

* The Signal Box Theatre will still host the infamous Last Night of Panto, in which the crew get their own back on cast, but it will be moved to a Sunday evening. Dick Whittington (and his Meerkat) will run from Thursday, December 10, 2015 to Sunday, January 24, 2016. People who already have tickets are asked to wait for their new tickets before contacting the theatre. Those yet to book should note that the show will not be on sale for several days until all bookers have been transferred. Visit yorktheatreroyal.co.uk for more information.