West End theatres have an average of just one toilet for every 38 female audience members, according to research by The Stage.

The research calculated that women would need a 57-minute interval for all to visit the bathroom, but the average interval is 20 minutes.

The Old Vic had the most limited facilities, with just one toilet per 56 women. Many theatres have listed status and struggle to increase the facilities: the Old Vic itself is a Grade II-listed building.

The modern National Theatre came out on top of the survey, as it has one toilet for every 20 women.

The Stage reported that average-sized West End theatres should have a minimum of 45 women’s toilets, but on average they have just 25. When combined with the figures for men’s toilets, there is an average of one toilet for every 26 audience members.

British Standard guidelines state there should be two toilets for up to 25 women, with one more for every additional 25 women at theatres.

Disabled toilets fared even worse: 62% of the 42 surveyed theatres had just one disabled toilet, and both the Ambassadors and Wyndham’s theatres offered no disabled toilet access at all.