Theatre bosses say they’ve had to tighten up security after the terrorism threat level was raised to critical.

The Marlowe Theatre in Canterbury issued the advice to patrons warning them that security will be beefed up as part of extra measures being introduced.

In a statement on the theatre’s website, it warned guests that bags might be searched by security teams and advised against bringing larger bags to the city centre venue.

The news emerged as the theatre hosts the West End play War Horse in one of the longest runs from a national production to be staged in Canterbury.

The security alert follows the terror attack at Parsons Green Tube station on Friday, and the arrest of a teenager at the Port of Dover yesterday.

Last year Kent Police said there would be more armed officers on patrol at tourist sites in Kent, including Bluewater and Canterbury Cathedral.

Then in the wake of the Manchester atrocity in May, armed officers carried out patrols in town centres and at other busy locations in the county.

The theatre statement said: “In response to the national threat level being increased to 'critical', The Marlowe has introduced additional security measures as part of our venue's security policy.

“We would like to ask that, wherever possible, you leave unnecessary bags at home. Small bags will be acceptable, but these may be searched by our team. Medical items and baby changing equipment are permitted.

“We’d also advise that you arrive earlier than normal, as entry will take a little longer than normal.

“We appreciate your patience and understanding on this matter and if you have any questions please call our Box Office on 01227 787787.”