YORK Theatre Royal will mark its 275th anniversary by throwing open its doors for a weekend of family fun and frivolity from August 9 to 11.

For three days, the theatre will be packed with tours, exhibitions, taster sessions and feasts – and the promise that "it’s going to be one big party".

There will be free 30-minute guided tours of the theatre when people can enter the hidden backstage world, discover the secrets of the Grade II listed building and find out plenty more about its fascinating history.

The St Leonard's Place building, which dates back to the 18th century, is a patchwork quilt of many periods: originally built over a 12th century hospital, with many changes over the years.

These have given the theatre a Georgian interior, Victorian façade, 1960s' poured concrete addition and now a £6 million transformation into a building fit to serve a 21st century audience with improved access and flexibility. The tours are free but booking is advisable.

Look out too for a ghostly look behind the scenes in a Digital Ghost Hunt, suitable for age eight upwards. Renowned actor and ghost geek Julian Fitzmaurice will lead an expedition exploring the spooky goings-on that have happened at the theatre over the centuries. Will the Grey Lady and the Dandy materialise as ghost-hunters stalk the creepy corridors? Tickets cost £5 for over 16s, free for under 16s; again booking is advised.

More stories will be told in the De Grey Rooms next door, which will be transformed for the birthday weekend and house a costume exhibition showcasing the array of outfits from the costume department.

Pauline and Claire, from Costume Hire, will be on hand to tell the stories behind the costumes in this rare chance to see clothing and accessories from the theatre’s story of precious items, plus hand-drawn designs from past productions, as well as vintage and antique items.This free exhibition will be open from 11am to 4pm on August 10 and 11.

Nobody will go hungry during the 275th birthday celebrations. A barbecue on the patio will offer lamb and chicken shawarma and grilled halloumi, all served with pittas, tabbouleh, salad, Greek salad, tzatziki and hummus. The café will be selling a whole range of tasty sweet treats too; the Birthday BBQ will be open on August 10, 11am to 6.30pm, and August 11, 11am to 4pm.

York Theatre Royal Choir will be offering a free taster session. From vocal warm-ups to learning a piece of music for use in a theatre production, you will see "what makes the choir unique among York choirs". Saturday session timings are 11.30am to 12.15pm, then 2.45pm to 3.30pm; Sunday, 1pm to 1.45pm.

The theatre’s volunteer photography group will take over the foyer screens with favourite photographs taken of the theatre, everything from behind-the-scenes shots to production photographs.

The Friends of York Theatre Royal will be hosting a cake and crafts sale during the weekend. For full details of the 275th birthday weekend celebrations, visit yorktheatreroyal.co.uk. Tickets can be booked on 01904 623568, at yorktheatreroyal.co.uk or in person from the box office.

Charles Hutchinson