Quote
Places like Heathrow Approach at Terminal Control West Drayton allow controllers to be in position maximum of an hour and a half, then a 30 min break (it be the law!).
Unquote
Actually, it's not law, it's a local agreement called Enhanced Relief. If you are forced to exceed the 90 mins, you can raise a report for local management, but you are not in breach of SRATCOH until you exceed 2 hours.
(SRATCOH: Scheme for the Regulation of Air Traffic Controllers' Operational Hours (or something!))