I honestly don't know if these two are in genuine need or not but I know how easy it is to get caught up in these things and your heart rules over you head, and that's how even the least gullible people can get duped.

So let me ask a few questions for your consideration (I'm originally from London so most of this is with domain knowledge):

1) I'm surprised to hear homeless people hanging out on Picadilly in Mayfair. Rightly or wrongly they often get moved on as that area is up-market, as you know. Therefore homeless people hanging around there are quite often the opportunistic ones who come in to the area to sit for as long as they can because they know that they'll be passed by some of the most affluent folks in London and so the chances of getting money is greatest.

If these two were genuinely homeless then they would have been moved on from that area so you have to wonder whether they were instead grifting. A popular grift in that area is for a guy to come up to you and say he got a call that his wife is having their baby in the hospital so he was driving on his way there but his car ran out of petrol and he forgot to bring his wallet.. could he have £5? That is a classic grift in Mayfair and The City because £5 is nothing to most people there and I've had it pulled on me a few times without success.

It's worth nothing that a lot of grifters will take the tube into the city, pretend to be homeless, take £200+ a day, and then take the tube back out to the suburbs where they live. That's £50k+/year tax free and will rent you a house! That kind of grifting is pretty common esp in the touristy areas.

2) If they are from Transylvania then they are Romanian, which makes them EU citizens. As a homeless + pregnant EU citizen she would probably be entitled to emergency support from social services. If he has worked here an paid NI then they would almost certainly qualify.

May I ask if they represented themselves as "Transylvanian" or "Romanian" because if someone tells me they are Romanian then I would immediately say that they are EU. If you say "Transylvania" then it sounds more obscure/etc - which is also a classic confidence trick. Transylvania is not a country and so it would be an odd place to announce you are from in a foreign country.

3) Creating an artificial sense of urgency is another confidence trick (like the "my wife is having a baby" example above). Calling you at 1am and saying they have no bed tomorrow seems to be in line with that. Why did they call/text at such a late hour and not in the morning?

4) I had a friend who owned a number of flats in a building and he let some homeless people stay there to 'get back on their feet'. Instead of utilizing his kindness to get on top of things as quickly as possible they just dossed and squatted there as long as they could and then when he got pushy to have them leave they trashed the place and tried to set it alight. Even if these two are real, some people have unusual mentalities in which they can only use help to survive and don't have the ability to use it to get back on their feet. In other-words two weeks in a B&B might just take their burden off for two weeks rather than actually use it to get to the next level.

My ultimate advice would be to contact social services for Kensington and Chelsea (which I believe to be the borough for that area, see http://www.rbkc.gov.uk/housing/homelessness.aspx), who frankly are well resourced compared to other boroughs. It might be they have to go back to the borough where they last lived but as a pregnant woman they would probably assist her with that.

I would also contact Shelter and other homeless organizations as I bet they would take her on priority as she is pregnant.

(Assuming she is pregnant, which is another classic grift.)

Perhaps I'm being overly cautious, verging on negative above, but it sounds like you're pretty taken in and so I'm just trying to create some balance. I'm also minded that with so much resources and support for homeless people in London, certainly compared to here in San Francisco where there is nothing, there is no real reason for anyone to be homeless in Central London unless they are refusing assistance, are drug-dependent and won't enter rehab or are grifting.

I was going to leave out my judgment and leave this to you to decide, but I decided to add post-edit: it's almost certainly a grift. Esp waiting outside the Ritz, which you present as being ironic/juxtaposition but that's probably by design. The 1am text seems grifty too (totally unnecessary time to text, false sense of urgency).

I think the best thing you can do right now is to help them with access to these services rather than giving them money. If they are real they'll accept the help and if they are grifting the'll push you a mile away because they know its a route to getting caught.

Let us know what happens!