I would be interested to know the total production number of Colts - 10,000 over five years or about 2,000 per year sounds plausible but it would be good to get confirmation from the archive ledgers. Something to follow up on when i'm retired!
There must be more than 60 Colts out there as they come up regularly (6 or 7 times a year) on ebay. It also depends on what is meant by 'survives' it could be anything from a box of bits in a shed, to taxed, insured and running on the road. Maybe the AOMCC secretary could tell us how many members have one - as we put this info on the application forms when we join the club.
Having rebuilt a Colt i estimate that it is about 50% BSA parts ("straight off the shelf") and 50% of parts that are unique to the Colt (it doesn't borrow any parts from the rest of the Ariel range) so it is an outlier from the Ariel family and has more in common with the C10-11-12 range. I don't know what was going on in the BSA marketing dept at the time but judging by the adverts they were pushing it as a more upmarket entry level bike than the BSA C range.
Ariel Square 4 mk2, Ariel Square 4 mk3 (yes, really), Ariel Colt, Matchless G12, BSA C12. Room for one more......