Didn't think it would be this much later...
Anyway, it runs something like this.
RAF sqns can be awarded their standard after completing 25 years of service (obviously, the unit must be extant and periods of disbandment are not included in the tally) or by 'earning the sovereign's appreciation following specially outstanding operations'.
120 and 617 are the only two sqns to fall into the latter category, which is why they have (or seem to) 'special' status when considering seniority, etc for disbandment/re-equipment.
All the other sqn numberplates are allocated/avoid disbandment on the basis of seniority. The Air Ministry and then MoD have drawn up lists of which units are the most senior in the air force, and these can be found in the PRO.
Obviously, the 30 year rule applies to these documents, but the order in 1973 was:
II(AC)
1
6
4
14
24
8
60
5
12
70
3
25 etc (there are 171 listed in total, so I'll stop there)
The order for the Nimrod sqns in that list is:
201 (43rd in seniority)
42 (77th)
206 (91st)
120 (98th)
All of them will have advanced since then, since some units ahead of them in 1968 are long gone, and will have slipped down the list.
If the precedent pertaining to standards is followed, then as J.A.F.O says, 206 will be the unlucky numberplate.
NB, though, that the rule does not always apply: when the F-4J entered RAF service, the number plate should have been 39 rather than 74, as the 39 plate was free (39 having disbanded and become 1 PRU in 1982 before the PRU was rebranded as 39 (1PRU) later on).
<removes anorak>
Last edited by Archimedes; 5th Dec 2004 at 16:54.