For the first series of Blockbusters, they actually didn't. The ident was played in live on transmission, because they knew when that series of Blockbusters was being recorded that the Central ident would change in the middle of that series on transmission, but the new ident hadn't been created yet. So they left it without a front ident, for those at Central TV in Birmingham (where the tapes of Blockbusters were transmitted from after the Elstree studios closed in July 1983) to play out live before fading or cutting to the videotape recorder playing Blockbusters. This practice also lenses itself to Blockbusters being repeated in Channel 4, which the first series was repeated on in 1984, as Channel 4 never broadcast front ITV idents so there was no need to faff about editing the ident off just for a Channel 4 repeat. Most ITV programmes in this era had the idents actually recorded on the same videotapes as the programmes themselves, but the above practice was not unusual. Southern TV did it with Worzel Gummidge, I think Yorkshire TV did it when One Summer (originally a 1983 Channel 4 programme) was repeated on ITV in 1985 and some ITV companies did it when they broadcast films or imported programmes.
Original ITV broadcasters does feature the original Central "Moon" bumper from 1982-83 before the intro of Blockbusters starts.
For the first series of Blockbusters, they actually didn't. The ident was played in live on transmission, because they knew when that series of Blockbusters was being recorded that the Central ident would change in the middle of that series on transmission, but the new ident hadn't been created yet. So they left it without a front ident, for those at Central TV in Birmingham (where the tapes of Blockbusters were transmitted from after the Elstree studios closed in July 1983) to play out live before fading or cutting to the videotape recorder playing Blockbusters. This practice also lenses itself to Blockbusters being repeated in Channel 4, which the first series was repeated on in 1984, as Channel 4 never broadcast front ITV idents so there was no need to faff about editing the ident off just for a Channel 4 repeat.
Most ITV programmes in this era had the idents actually recorded on the same videotapes as the programmes themselves, but the above practice was not unusual. Southern TV did it with Worzel Gummidge, I think Yorkshire TV did it when One Summer (originally a 1983 Channel 4 programme) was repeated on ITV in 1985 and some ITV companies did it when they broadcast films or imported programmes.
*lended itself, not lenses itself