The Daleks invaded Buckingham Palace as stars of Doctor Who past and present attended a reception to mark the 50th anniversary of the show.
Props from the show, including two versions of the Tardis, a pair of Daleks and K-9 the robot dog, were set up in the Palace's Bow Room.
Matt, whose stint as the Doctor ends this year when he will be replaced by Peter Capaldi, said he was "really thrilled" to be invited along and admitted that part of him regretted quitting.
He said: "You know, just seeing all my old friends who I work with, they're all here, and the kids having a good time and the actors...
"It's a great job but I left, so no point crying over spilt milk, is there?"
The actor also said he would not rule out a return on another anniversary: "Who knows, in another 50 years, if they let me come back, I will, and as of Christmas Day it falls to Peter and I wish him all the best."
Others attending the reception for cast and crew included current star Jenna Colman.
The series celebrates its 50th birthday this Saturday with an anniversary episode on November 23 called The Day Of The Doctor which features Matt as well as his predecessor, David Tennant.
Tom Baker, who played the fourth doctor, said the show's appeal was down to the fact the character was not a "do-gooder" but could be "naughty", "cynical" and "very silly" and said it was the highlight of his career.
He said: "Everything as an actor after Doctor Who was a little bit downhill really so what it meant was going from Doctor Who to Macbeth or An Inspector Calls, it was just Doctor Who up there all the time and I used to go on and do it in the style of Doctor Who and all the other actors would hate me but I couldn't help that. I didn't do it for the other actors, I did it for whoever bought the ticket."
John Hurt, who has been briefly seen as a previously-unknown incarnation of the Time Lord, said he first became interested in the show because Tom "used to talk about it with such enthusiasm".
He said: "He was absolutely obsessed with it and now I realise if you're playing the Doctor you would be."
Peter Davison is not appearing in the anniversary episode, but did say he had been busy working on a "project that will be around on Saturday" and available for fans through the BBC but declined to go into detail.
Doctor Who holds the Guinness World Record for the longest-running science fiction series in the world.
It began on November 23, 1 963 with William Hartnell as the Doctor and there have been 11 Doctors to date.