I was under the impression that the number in any given squadron on any given day was a bit of a movable feast in any case, but happy to stand corrected. FWIW I agree with those who say that he dealt with the MP's trolling comment pretty well, courteously and straight bat.
For those arguing that numbers of squadrons are unimportant compared with airframe numbers, in this instance a sixth sqn would imply the retention of some Tranche 1s, which has been talked about, so pushing airframe numbers beyond the 107 that there'll otherwise be after T1 OSD. Bearing in mind that in 2020 there are due to be just 6 front line FJ sqns in total, an increase of that kind could only be a good thing. And to repeat, he DID say there would be 6 Typhoon sqns in 2020. The written record has since been "corrected", either because he was wrong or because he shouldn't have said it.