[WillPS]

As Blockbusters was never networked it's probable the globe only ever appeared when Central were feeding it around the network for local playout and thus it was seen on the original transmissions.

I think the frontcaps were only on stuff that was networked, though I'm probably wrong on that.

When Central did the whole "Central Presents..." followed by an ATV frontcap, that was done live, though it eventually only appeared on the schools programming once all the mainstream stuff ATV had made prior to 1982 had gone out.

Can't remember if Family Fortunes was networked before Les Dennis.

Nah, the ident was definitely baked in on the master tapes. In later series it was quite clearly integrated in to the title sequence, that's not something they'd be able to achieve adding it on in playout. If they didn't want to show the ident they'd simply wind the tape forward past it - I'm sure there's a clip of the Thames ident being wound through during an early CITV somewhere?

The Central Presents ident might have been added on the front of ATV stuff live for a time but I suspect for the schools programming which was often repeated it was added to the front of a new copy of the tape, for simplicity.

Family Fortunes was networked from the start AIUI.

With Family Fortunes, Challenge have a mixture of original tapes intended for UK broadcast (including contestant calls in some cases, with and occasionally without attempts to hide it) and also copies spun off by CTE/Carlton International for non-ITV/international distribution. Probably the same with Blockbusters and accounts for some of the episode-to-episode changes.