Concerns that this month's GayPride festival might lose out because it clashes with the season finale of Doctor Who have led organisers to show the sci-fi favourite on giant screens in Trafalgar Square.
Jason Pollock, chief executive of the Pride event, said: "We hit on the idea of screening Doctor Who at the end of our main stage show in response to demand. Doctor Who is probably the most gay friendly show on our screens and many people were anxious not to miss the last programme now everyone can celebrate Pride and Doctor Who at the same time!"
John Barrowman, star of Torchwood, and the Doctor's current companion, played by Freema Agyeman, will discuss the show at the event earlier in the day.
Show producer Phil Collinson said the team were very proud of this "spectactular and defiantly not-to-be-missed episode".
Events in Trafalgar Square start at 3.00pm on 30 June following the march from Oxford Street. Doctor Who starts at 7.10pm.
GayPride expects to attract about 500,000 visitors.
More here on the GayPride website.®