They are run by a couple from Yate and the female of the couple has been mentioned here recently under the name Coco offering services. I've attended their parties in the past but haven't been able to cause of work and other diary clashes.
The parties are held in an appartment in central Bristol in Cabot Circus above the shops, cost was £5o but think that's gone upto £60, a £10 deposit is required by bank transfer and final payment on the door contactless. Parties are only two hours from 8-10pm with a buffet and soft drinks supplied as are condoms which are a must. The girls aren't pros, just keen amateurs, usually in the 40-50 age range though you may get girls out of that age range.