Heritage Arts Company are currently organising the third edition of VAULT festival, a six-week event programming all kinds of performance into the network of tunnels near Waterloo Station (formerly the Old Vic Tunnels, and before that a storage facility for British Rail).
The next edition of VAULT will run 28 January - 8 March 2015. About one-third of the programme will come from open applications, with shows having a one-week run (in one of the venue's several spaces), and the artist/company receiving 80% of the box office sales.
For more information and to apply see here. Deadline is 19 September 2014.