Try the Netherlands or Germany. Spotted a Dutch escort site with a lot of faces I recognised when I was over there last year. Tried to book one I had seen many times in London, but unfortunately not available that day. Also far more escorts available on my trip to provincial Germany than I recall from my previous visit there, admittedly quite a few years ago.
From what some of my long-time regulars have told me, they have taken a significant hit to their earnings over the last year or two. The massive drop in the value of the pound since the referendum has meant they now take home significantly less euros for every pound they earn. We only notice it when we go on holiday, they see it every month they send or take their money back home.
Unfortunately, there are also now big issues about whether they will be allowed in after March. A lot who have been living over here for many years and have applied for settled status have had it refused. Don't believe what the politicians say about it being simple to get! They are now very worried that if they go back to see family, they won't be allowed back into the UK.
All of which means that, for a girl deciding whether to work in the UK or in Germany, the UK is nowhere near as attractive a prospect as it used to be. Germany looks a far better prospect.
Not all due to Brexit (the influx of Romanian competition has also affected earnings, for example), but it has certainly been a significant factor.
Agreed that there is "natural wastage", most girls will only work for a limited time, until they have earned enough or until they have had enough of the work. This has always been the case. What has changed, is that we aren't getting the new faces to replace them in anything like the numbers that we used to.