Mike Smith was the presenter, and his episodes are always skipped.
What's the reason the Mike Smith episodes aren't shown?
Supposedly it's because he didn't want them shown, though as far as he's been discussed, we think there's techically no reason for the BBC to get the presenter's permission (or his estate's, in MS's case), and they could just show them anyway.
BBC 4 did show the 1982 Christmas special (co-presented by him) back in 2008 with no problems, so it's a bizarre situation really.
There's been lots of "theories" about why the BBC are doing this even though they don't have to, but I doubt we'll ever know the full reason. The fact they included a clip of him in the Story of 1985 last week has just complicated the issue further.
It's frustrating though- particularly has he was the most prominent presenter in 1985 & 86 (and second most in 1987).