OP as you are in England you have even more ammunition because it is clear, as you and others have said, it is the design that is different. From what you are saying, single sex designs (toilet in a cubicle then a shared sink?) are being used for both sexes. I am not clear what the current provision set-up is but here’s a few bits you may find useful:
HSE (regarding Document T) that says only toilets in a single sex environment can have door gaps. Therefore if the toilets have door gaps they have to be in a single sex environment before the cubicle doors. I had this clarified in an email.
Document T only is for refurbs and toilets from 2024, but it would be a ‘brave’ venue to argue with HSE that single sex designs were suitable for mixed sex. As far as I am aware, no mixed sex provision has ever allowed door gaps. I would suggest that the Sexual Offences Act would need to be revisited if so.
There is also Document M which is for accessibility: https://assets.publishing.service.gov.uk/media/66f6c5eec71e42688b65ee11/ADM__V2_with_2024_amendments.pdf which states that to satisfy Part M1 and M3 at least one WC cubicle is provided in separate-sex toilet accommodation for use by ambulant disabled people.
There are so many reasons unisex toilets are less safe and healthy, particularly in a hospital. There’s 4 health and safety reasons why single sex toilets have door gaps: ventilation, cleaning, supervision (in case of medical emergencies), and prevention of misuse (including preventing sex and drugs).
As hospitals and care settings will have more ill people, and people when they feel really ill may rush to the nearest toilet, it is not surprising a lot of people collapse in hospital toilets. We need them to be as safe as possible. For example up to 11% of cardiac arrests happen on the toilet. It’s upsetting that people can be left for days in private designs of toilets in a setting best placed to help them. https://pmc.ncbi.nlm.nih.gov/articles/PMC3590314/
The pathogen plume that covers the immediate area everytime someone flushes, will cover the sink and dryer in a unisex toilet. If the sink is in the room outside the toilet cubicle, it will have less particles from the previous occupants flushes, so you will be washing your hands in clear surroundings.
Here’s some recent scientific research on how unisex toilet designs are the best for high pathogen numbers:
https://salus.global/article-show/pathogen-findings-raise-concerns-about-move-to-unisex-hospital-facilities
Here’s the WRN report on sexual assaults and rapes in hospitals:
https://www.womensrights.network/hospital-report
and here’s the WRN pictures to show what problems occur when you try and use a single sex design for both sexes:
https://www.womensrights.network/school-toilets
It’s obvious why toilets in a mixed sex environment should have complete privacy. Voyeurism is so common in toilets you should be able to find a local case if you google. However be careful how you do this. Do not put ‘voyeur’ first because you’ll get lots of results on websites with pages of footage from toilets. Obviously setting up a hidden camera helps if you have legitimate access, it’s completely private and there’s lots of places to hide it. Ironically unisex toilets provide the best opportunities for men to do this.
So many examples in hospitals include
https://m.belfasttelegraph.co.uk/news/health/man-arrested-after-recording-device-allegedly-found-in-belfast-hospital-toilet/a1600040325.html
https://www.bbc.com/news/uk-england-30196241.amp
https://www.independent.co.uk/news/uk/crime/airbnb-hidden-cameras-doctor-jail-voyeurism-b2747307.html
https://www.bmj.com/content/373/bmj.n944
It’s a worldwide problem. This one shows the potential problems for a hospital in Australia as the nurses want to sue:
https://www.carbonelawyers.com.au/case-files/nurses-doctors-could-receive-big-payouts-from-melbourne-hospitals-after-they-were-allegedly-filmed-in-toilets/