The first Merlin GR1 squadrons would most likely have been 7, 12 and 15. 12 had been identified as the obvious choice for one squadron in about mid-1965, while the other two numberplates were retained by Bomber Command specifically for the aircraft when there was some chopping and changing of the ownership of some numbers.
To explain that point:
If a squadron (say number 74) was a fighter squadron, it'd be in Fighter Command (obviously). Fighter Command therefore 'owned' the numberplate. However, if the squadron disbanded and there seemed to be little prospect of it reforming in the foreseeable future and if the numberplate was a particularly senior one, the AOC-in-C of the Command which owned it could transfer it to another Command if that Command was casting about for numberplates for a new squadron.
Thus, in 1965, Transport Command was after a numberplate for the VC10 squadron. Bomber Command offered up 49, 90, 148 and 207 (recently disbanded Valiant squadrons) since it seemed unlikely that these would reform as bomber units in the near future - which they haven't. However, in January 1966, the AOC-in-C Bomber Command wrote to the Air Member for Supply and Organisation outlining future plans for the Command. 7 and 15 were to be retained as the F-111 squadrons, and the 40 Squadron numberplate was also to be retained - implication being that 40 would receive the F-111 or possibly AFVG in due course. In this letter, Sir Wallace Kyle told AMSO that as 10 Squadron was a senior numberplate and not likely to be employed by Bomber Command, he would be content to transfer it to Transport Command for the VC10.
Conversely, since 10 Squadron formed on the VC10, the numbers offered for transfer in 1965 remained under the controlling authority of Bomber Command, and would've been in the running if there'd been an expansion of the Command for some reason.
Clearly, this sort of horse-trading of numberplates all-but ended when Strike Command was formed and concluded entirely when Air Support Command was brought under the Strike banner as well.
The Buccaneer numberplates originally projected are interesting ones - Under a plan in 1970, 12 was to be the first Bucc unit in Strike Command, followed by 208, then 58 and finally 45. 100 Squadron was also mooted as a possibility in 1968, but that'd have been as an alternative to 208, which under the 1968 considerations might have received Phantom FGR2s. 15 was to be the first RAFG Bucc squadron, and 16 the second. Clearly, the four-squadron Bucc force in Strike Command declined to being a three-squadron force, in which case 58 wouldn't have formed as the junior of the four plates under consideration; it'd have ended up as the lead Hunter FGA9 unit at Wittering, and might then have ended up as the Tornado Weapons Conversion Unit.
Anyway, back to the F-111.... I suspect that the temptation to field a couple of squadrons of ex-RN Buccaneers would've led to the RAF deciding that they might be able to use it (Cyprus? Germany?) after all, in addition to the AFVG/UKVG/Must Refurbish Canberra Again; I'm sure some pressure from SACEUR and the US President might have squeezed the money for a two-squadron nuclear QRA force out of the cabinet; an OCU plus one maritime squadron at Lossiemouth would've been useful and freed the F-111s up for their intended mud-moving/irradiation of Her Majesty's enemies role without having to bother with Martel. With the failure of AFVG, it might not have been impossible for the RAF to have 50 F-111s, 50 Buccaneers and a small force of Vulcans - say three squadrons at Scampton plus the OCU - with the intention to replace the Buccs and Vulcans (and possibly the F-111s) during the early to mid 1980s with what became the Tornado.