Cambridge Parties haven't had an event since the raid.
There's the pricey Le Jeu in Peterborough.
The Vanilla Alternative swingers club at Tempsford (on A1 twixt Sandy & St Neots) hosts some events, some may have guaranteed action.
Jaydees swingers club nearby (rural location twixt St Neots & Bedford) also hosts swinger parties.
Other than that it's Northampton, Birmingham or London.