For the benefit of chassis-orientated anoraks, the last 427 chassis/body to leave the AC factory before it upped and staggered off to Malta, was numbered COX5012. It has been documented as such and photographic evidence exists (confirmed by Brooklands MoCo). This could be regarded, if you wish, as the very final act by AC Cars in the UK. The red 427 is, I am informed, 5003 and has existed as a rolling chassis for some time - and there may well be others out there, awaiting completion. But the very last, by date and number, is 5012.
The above does not discount the possibility that more ali-427s might one day be available, as the AC website states. There will be an announcement about this in the days and weeks to come, although such cars will be 'non-UK-AC' models(!!)