I saw this last Wednesday afternoon and it is really splendid. I'm not sure if the special £5 deal seats are available, but worth a shot.
£5 COMMUNITY WEDNESDAYS FOR LAMBETH AND SOUTHWARK RESIDENTS
Peter Gill directs Rosamund Pike, Kenneth Cranham and Andrew Woodall in Patrick Hamilton's Victorian thriller Gaslight, the powerful story of a young woman psychologically dominated by her husband.
While Jack Manningham is out on the town each evening, his wife, Bella, stays at home alone, believing she's losing her mind: she can't explain the disappearance of familiar objects or the ghostly flickerings of living room gaslights. Questions about Jack's behaviour and true identity are aroused following the unexpected arrival of Detective Rough.
£5 offer valid for Wednesday matinee or evening performances (2.30pm and 7.30pm). Book in person at The Box Office only bringing proof of address. 2 tickets per booking maximum and tickets can be booked in advance. Group bookers should call Rachael Stevens on 020 7902 7596.