If in UK, ladies changing rooms in swimming pools and gyms are open, why are men allowed in if they say they are a woman?

I was out shopping yesterday in a well known chain store. They have separate mens and womens changing rooms.....but.....the ladies now says outside 'female and any gender' changing rooms and the first section of about 6 cubicles state 'any gender' on the curtain.

I thought it odd.....as 'any gender' implies men can go in those too......yet they have separate mens facilities.......