I was quite shocked watching a DVD of The Two Ronnies to see a late 1983 episode (Series 10 Episode 1) with Ronnie Barker blacked up, in the same manner as the Black and White Minstrels. I really was shocked and surprised by this, and by how relatively recently this had been broadcast.
Consulting Wikipedia (http://en.wikipedia.org/wiki/Blackface) I note that the most recent UK example of this noted there was a 1981 Are You Being Served? episode. Ignoring later (presumably ironic) examples such as Little Britain, can anyone think of still later examples of 'blacking up' since 1983? Benny Hill maybe?