P and O Cruises - what the actual fuck.

[Disappointedcruiser]

Apparently men using women’s toilets and facilities is fine, so long as they’re wearing a dress and wig. Really disappointing.

Who do I write to?

P&O Cruises does not issue a specific, standalone PDF policy regarding single-sex or gender-neutral toilets.
The cruise line's public facilities and guest standards follow standard maritime and public health operational guidelines rather than maintaining a separate code for public restroom access:

• Official Safety and Conduct Policy: The core behaviors and expectations for guests are governed by the P&O Cruises www.pocruises.com/essential-information/safety-and-security&ved=2ahUKEwiKnrTN2dOXAxXzVPEDHV_HCaIQy_kOegoIAggACAAICBAD&opi=89978449&cd&psig=AOvVaw16Euit2DZPGaBmsLo2jLZP&ust=1792967241396000" rel="nofollow" target="_blank">Safety and Security guidelines and their passenger conditions. This policy features a zero-tolerance stance on anti-social behavior, harassment, and disorderly conduct, which applies across all shared public areas on the ship.
• Public Restrooms On Board: Like most large cruise ships operating under modern regulations, P&O vessels feature traditional gender-segregated public restrooms (Male/Female) adjacent to dining and entertainment venues, alongside separate accessible/family single-occupancy facilities.

Perhaps you could contact the Guest Relations Team.

traditional gender-segregated

That's a bit of a contradiction.
Traditional would be sex segregated.
Perhaps they have been burying their heads in the sand ocean.

The use of restrooms rather than toilets or bathrooms suggest a strong American bias

I wonder because they’re at sea if any country has any jurisdiction over the Laws?

Yes this was my thought. Do they have to adhere to UK law while docked at a UK port and french laws while docked in France? Do they have to change it over once they leave British waters or is there some other international maritime law that they adhere to?

Yes. It's why the shops and casinos only operate once the ship is in international waters, to save having to navigate any local laws.

This might be a different company to the ferries, but P&O ferries sacked all their UK workers and replaced them with cheaper overseas staff. Not bound by UK law even when operating out of UK ports.

1. They are absolutely nothing to do with P&O Ferries. They are part of Carnival Group, an American company. They made it abundantly clear at the time that they did not condone P&O Ferries behaviour.

2. They are bound by Maritime Law and then the legislation of the relevant country whose waters they enter.

You will probably find similar policies for RCI, MSC, Disney, Virgin, Cunard, Celebrity etc. I'm not sure why P&O is causing such rage. Are you on board?

Vessels are mostly subject to domestic law in the territorial (12 mile limit) however maritime law sometimes trumps domestic law - for example the minimum wage and many other worker protection measures do not apply on vessels as the Maritime Labour Convention trumps UK law. In international waters the laws of the flag of the vessel apply, I think for most P&O vessels this would be Bermuda.

If you are on board and have had issues, go to guest relations. The staff are usually very helpful.

I think it will depend on where the ship is registered