Initialy, 360 was meant to bear the numberplate of a dormant unit. As it was to be a joint unit, it was suggested that 207 might be an appropriate 'plate, given its heritage as a former RNAS unit.
I forget why, but it was decided to start from a clean sheet of paper in terms of unit heritage and seniority, and 360 and 361 were chosen instead.
Although Jefford's bible doesn't have 188 squadron listed, there is some evidence that it got as far as getting some chaps together with the intention of it being a home defence squadron; however, before this was made official, the personnel earmarked for the squadron were sent to other units, and the formation did not go ahead.
606 Squadron was meant to form; it got to the point that squadron code letters were reserved for it at about the time of the Munich crisis.
Anorak off...