Buckingham Palace was held under siege by Daleks today. Well sort of: scores of Doctor Who actors and guests attended a very special 50th birthday celebration of the BBC sci-fi show ahead of this coming weekend's hotly anticipated anniversary episode.

The Day Of The Doctor
'The Day Of The Doctor' Will Celebrate 50 Years Of 'Doctor Who.'

DW stars new and old joined the Countess of Wessex at the palace for a royal party. Tom Baker, Peter Davison, Matt Smith and John Hurt arrived to defend the palace from daleks with current and former assistant Jenna-louise Coleman and Catherine Tate.

Smith, the outgoing Doctor who is set to leave the show via regeneration on Christmas Day, admitted that he was feeling emotional for his departure whilst surrounded by his DW friends. "Just seeing my old friends that I work with and the kids and the Daleks here and you think it was a great job, but I left. No use crying over spilt milk, he said, adding "Who knows, in 50 years if they will let me come back, I will."

Jenna-Louise Coleman Doctor Who
The 50th Anniversary Episode Will Feature Cast Members Old And New.

He then mentioned the new Doctor, who was named in the summer as The Thick of It actor Peter Capaldi. "As of Christmas Day it's on to Peter (Capaldi). I wish him all the best," said Smith, via The Telegraph.

See more photos from 'The Day of the Doctor' here.

Jenna-Louise Coleman, who plays the Doctor's current assistant Clara, revealed that she had already filmed a few scenes with the new Who, Peter Capaldi, adding that "he's definitely arrived." Other guests present included the BBC's Director General Lord Hall, programme writers, members of the production team and lucky children from two Cardiff schools who won a competition to design a royal TARDIS.

What the new Doctor be like?

Joanna Page David Tennant
Joanna Page Will Play Queen Elizabeth I.

This Saturday night's 50th anniversary episode, 'The Day of the Doctor,' will reportedly see Doctors from past and present unite. Former Doctors Tom Baker and Peter Davison were both present at the palace party spoke of the great "camaraderie" between each generation of Doctors. "I think secretly we all think we are the best Doctor, but there is great camaraderie between us," said Davison, whereas Baker's excitement was focussed on a rather royal compliment.

The Day Of The Doctor Smith Tennant Hurt
Matt Smith, David Tennant & John Hurt Will Make The 50th Anniversary Episode Exciting.

"[The Countess of Wessex] told me I was her favourite Doctor, which is very thrilling and very flattering and I will probably never recover," he gushed.

'The Day of The Doctor' will air on BBC1 on the 23rd November.