La Maison have spa baths in a few of their rooms. you need to book an hour minimum and tell them at the point of booking that you want the bath as it takes 20-30 minutes to fill.
Just a watch out though i've only booked it once and when I arrived there was no sign of the bath having been filled as they had either forgotten or not been bothered to do it

It's a bit like i've turned up at numerous parlours after asking for watersports and the girl hasn't been given the message by the maid
In my instance I was quite early and the session was going to start 10 or 15 minutes earlier than the booking time so I was able to wait a bit while they started running the bath otherwise I would have shortened the booking to 30 minutes
External Link/Members Only