Doctor Who: Who’s In The Day of the Doctor?

In a surprise piece of news, The Huffington Post has reported that Fourth Doctor Tom Baker will be appearing in The Day of the Doctor this Saturday in some capacity.
The Post claimed that the reveal came from an interview with Baker, in which he stated:
“I am in the special. I’m not supposed to tell you that, but I tell you that very willingly and specifically; the BBC told me not to tell anybody but I’m telling you straightaway. It worked out very well, I think, judging by the reactions of the technicians,”
We can take this report with the customary pinch of salt, but this rumour seems to have more substance than your average tabloid rumour – we only have three days to find out…
[Source: Doctor Who TV]