I've noticed on many photos that the bonnet fit is less than perfect, especially at the lower rear. It seems as if most cars are suffering from a slight frame sag or the radiator is a bit high? Also it seems worse on the offside.
Is this the case and how can it be checked without a major strip down. Am I being too fussy?
Buy an Austin 7 they said, It's easy to work on they said !
I think the problem is usually one of scuttle sag. I believe the body drop can be caused by the packing deteriorating and/or the baulkhead area becoming weakened by decay.
Personally, I would do exactly what Ruairidh's dad is doing, don't worry about it and get on driving it!
Next time it's off the road for an thorough overhaul, check the front body mountings and you can either jack those up or cheat and remount the radiator under the flitch panels rather than over them!
A bit of sag in the chassis offside may be the result of that point being weaker where the steering box mounts. Mostly it seems evident after at least 50 years of use, and is less likely if the car is used by persons of modest weight throughout its life. It's only my theory but it fits the facts.