Does she receive a good amount of bookings, some members here probably charge similar amounts but that may not mean they make a particular level of income or profit.
How much are her premises, what about insurance, professional registration, advertising, CPD?
How de heck I know

she works in one of Marylebone clinic and does Skype bookings too. Her Skype bookings are like £105 so I guess she always pay that percentage to clinic from 150ph
Yes, she is accredited.
Probably yes, although I do not think she works 8h a day. Surely not 5 days a week too. I guess she works like 3-4 days a week?
But it's her only job and she affords to live in central London.
p.s. you are asking about advertising so that's why I mentioned that she is entrepreneur. She knows seo, she links herself much. she has active insta and fb pages. she writes articles and yes, everything goes by getting yourself known. I wouldn't say you just start and suddenly by being in clinic you get 10 clients a week, no. you have to do pretty much similar stuff that escorts do