Of course I remembered that Louis Mahoney, who plays Old Billy
also appeared twice in Old Who, as a newsreader in the Third Doctor story Frontier in Space
and as dispensable crewman Ponti in the Fourth Doctor story Planet of Evil.
I had forgotten however that Richard Cant, who plays Kathy's grandson Malcolm in Blink
is the son of the late, great Brian Cant, who appeared twice in Old Who - as the doomed Kert Gantry in the first, lost episode of the First Doctor story The Daleks' Master Plan
and then as the equally doomed Chairman Tensa in the Second Doctor story The Dominators.
Blink of course turned out to be just the beginning of the ongoing continuity of the Weeping Angels; but its links go backwards as well as forward.