Actually it's stalling in traffic which is my biggest concern but getting the necessary parts to add a starter motor is proving difficult (or expensive). I think I'll just go over everything again including the carb and timing then, if all else fails, get a can of easy-start.

Location: Paignton, Devon

Is your Mini SU one of those with a little flexible pipe feeding the base of the jet? If so it could be the problem. I would check to see whether it is perished or restricted. I have never used one, the SU's on my cars are pre-war!

If everything is correct your car will start instantly, in good condition and properly set up A7's are generally very easy starting cars irrespective of the carb. If the problem is carburation I would suggest low fuel level, wrong needle meaning the jet is set too high to compensate and starting mixture will then be weak, or the enriching device (choke) is not working.
low compressions, worn valve seats, ignition faults will all cause problems

Location: NZ