The Mini was a Morris, of course, not an Austin.
When Austin and Morris joined together in 1952 to form BMC, Alec Issigonis came from the Morris side of the fence where he'd already designed the Morris Minor long before he designed the Mini Minor.
So, was 621 AOK the first Mini (Morris Mini Minor)?"According to retired BMC engineer Peter Tothill, who was responsible for the design and supervision of the Mini production line at Cowley (Morris) and performed rectification work on Mini prototypes, 621 AOK
was the first production Mini. Peter Tothill’s story is that four employees – Bob Moore, Tony Monk, Bob Hollis and Peter Tothill himself – built 621 AOK over the weekend of Good Friday 27 March to Easter Monday 30 March 1959.
‘There is absolutely no doubt in my mind, because on the Wednesday of that week, Les Ford (chief planning engineer) said to me, “We want you to build the first ADO15 over the Easter weekend when there will be no-one in the factory, and I want you there.” I had recently got married and we had planned to go away for the weekend, so I had to tell my wife that the trip was off! The car was loaded onto a truck, sheeted up and delivered to Longbridge (Austin) on the Tuesday, ready for the directors to view on the Wednesday. Tuesday was a holiday in Birmingham because they always worked on Good Friday.’
This version of the Mini story has it that (Morris Mini) 621 AOK was used as the reference for Longbridge foreman Albert Green to build the first Austin Minis. Peter Tothill reckoned it was impossible for Cowley to pilot build ten ADO15s in one day and that these cars were built in the preceding weeks with records commencing on 8 May 1959."
http://www.aronline....history-part-1/