In the days of three FLS the FAF was 34 single seaters for the frontline, plus 2 twin seaters. 20(R) had approximately 10 single and four twin seaters. Some were on loan to BAe, others in the JUMP programme, 41 Sqn had a couple, CAT 3 plus repairs were being done on some more etc. If you totted up 'all the GR7/9 in the UK' you got to about 73.
Apply a standard deviation of about 2 to all the above figures and you won't be (far) wrong.
As far as I am aware, the reduction from 18 to 10 FE@R didn't result in the disposal of any airframes.
What the above does gloss over is the 'fleets within fleets' issue. Not all of these frames would be 107 Cap E(A)s.
Not that this should in any way be taken as my opinion on whether or not it's coming back. It isn't - crying shame, but it isn't.