Isn't it illegal for two girls to work from one flat? Sorry to ask, or are the authorities indifferent about it?

Yes, it is illegal. That applies whether or not..

.. they are working there at the same time,
.. intercourse is on the menu,
.. any money is involved - thank you, a bit of 1920s class prejudice!

The consequence of all those is that there are a LOT of 'brothels' out there. Fortunately, it's only the people who own / run / 'control' the place who are breaking the law. Anyone who just works there isn't.

Whether or not anyone cares depends on where you are. The first question I used to have to ask when rung up with questions like this is "where are you?" Some police forces went after people subletting their work flat on their day off, other forces would invite the owners of mega-brothels onto committees to help ensure they were run better.

My then local police had a target of raiding a brothel every quarter. There were more than four brothels on our street, never mind the rest of the borough. One was on the front page of a tabloid for a couple of days (some politician met his boyfriend there) but it was never touched and is probably still going.

Now.. hardly anywhere cares unless there is serious other criminality, like underage workers / selling drugs involved.

But one of the basic rules of sex work - don't annoy the neighbours - is particularly important in this context. Piss off enough (or the wrong) neighbours, and even the 'we don't care' police areas will be interested.

So two girls working from a two bed flat isn't really cared about and generally risk free?

If we're going to split hairs then 'girls' would be unacceptable regardless of the context, since it's illegal to pay anyone aged under eighteen for sex.

Two adult women (or men) working from the same flat is unlikely to attract much interest on it's own, but nothing is risk free - the ideal neighbour can move out and some nosey bastard who sits at home all day can move in, or you can wind up being rumbled because of somebody else in the flats making a pain in the arse of themselves (including punters) and drawing attention to everybody.

The likelihood of police being bothered is still very low though; it's more likely you'll be booted out of the flat

So, if a landlord charges above the going rate for a flat and rents it out to prozzies, can the landlord be done for making money out of prostitution? Also, if the police did come round and arrested the sex workers, what should he or she do at the police station? Use the duty solicitor as that's free?