This is at the very least indirect discrimination on the basis of sex. That is women are unfairly disadvantaged, if you assume that both sanitary facilities are intended to be used by men and women.
Let's say there's ten urinals and six cubicles in one facility and sixteen cubicles in the other. Previously this gave men and women equal provision (which is still indirect sex discrimination, as it puts women at a disadvantage, because we need more than three times longer to urinate and have additional needs. This is why ratios in modern buildings are meant to be 2:1 or even 3:1 women vs men).
But let's say you started out equal.
Now both facilities are mixed sex.
Men: 10 urinals, 22 cubicles = 32 places to pee
Women: 22 cubicles = 22 places to pee.
Women have 68.75% of the provision that men can use.
That calculation assumes women are willing to use a space where men are in partial undress. Which most women are not, for various reasons, including privacy, dignity, safety and cultural or religious restrictions.
Taking this into account we have:
Men: 10 urinals, 22 cubicles = 32 places to pee
Women: 16 cubicles = 16 places to pee.
Women have 50% of the provision that men can use.
There are building regulations that specify exactly how many male and female toilets an entertainment venue has to provide. (Usually calculated per 100 or 1000 visitors). I believe that the Playhouse is in breach of those regulations.
The relevant regulation is:
British Standard 6465 (1:2006+A1:2009)
It says:
Note 1 In the absence of more reliable information it should be assumed that the audience will be 50% male and 50% female.
WC: Males: In single-screen cinemas, theatres, concert halls and similar premises without licensed bars:
1 for up to 250 males plus
1 for every additional 500 males or part thereof.
WC: Females: For single-screen cinemas, theatres, concert halls and similar premises without licensed bars:
2 for up to 40 females
3 for 41 to 70 females
4 for 71 to 100 females
plus 1 for every additional 40 females or part thereof.
Urinal: Males: In single-screen cinemas, theatres, concert halls and similar premises without licensed bars: 2 for up to 100 males plus 1 for every additional 80 males or part thereof
(No entry for females next to this heading)
Calculation of absolute numbers must be based on 75% of total capacity. Which Wikipedia tells me is 786.
For each sex then the calculation must be based on 295 visitors.
For males that's 2 WCs and 5 urinals minimum. For females that's 9 WCs minimum.
That's the regulation they need to adhere to. If we assume the toilets were originally built as designed, they would now be in breach, as female customers only have 5.5 toilets if both spaces are mixed-sex, and 4.5 if women avoid the space with urinals.