When the interval curtain comes down at any of our most prestigious theatres, members of the audience take the opportunity to use the toilets. Men can be in and out in a few minutes. But women have to queue up because there are never enough cubicles. 

Often, the second half will start and women will still be waiting. It's uncomfortable, and may be painful too, especially if they have a bladder condition. It's also humiliating: no one wants to be seen queuing up when the queue spills out onto a public staircase or a corridor.

In short, women can be trapped for the whole 20 minutes of the interval, ruining the very events they had hoped to enjoy.

It's a disgrace that in the 21st century, women's needs are still not being met by organisations funded by the public purse. From the English National Opera in London to the Millennium Centre in Cardiff, it's the same thing: not enough loos for women. 

So I'm calling on our Arts Councils to require that all arts bodies that receive public funding should increase their tally of women's toilets up to agreed, modern standards. Toilets should either be gender neutral, or provision for women should be greatly increased. 

This isn't difficult to understand. Straightforward guidelines are laid down in "British Standard 6465-1:2006 Sanitary Installations" For entertainment venues where most toilet use takes place in the interval, there need to be only two WCs for up to 250 males and one more for every additional 250 males or part thereof. (That's because men can make use of urinals.) By contrast, there need to be two WCs for up to 20 women, plus one more for every additional 20 women or part thereof, up to 500 women, and one per 25 women or part thereof for over 500 women. It's a huge difference.

I teach my architecture students these principles, but architects rarely get clients to agree, if they even raise the issue: that's because architects and clients are mostly men. 

We can all do something, though. As long as cultural institutions discriminate against women in terms of toilet provision, we should not be backing them with public funding.

So please support this petition. Demand that the Arts Council sign up to basic humanitarian requirements, and require that those it sponsors upgrade their facilities - or lose their backing.

Thank you.

Stephen Games / New Premises - the Architecture ThinkTank