If the panel gaps are too good people will start looking confused at it and asking what is it, is it a Datsun of some sort?
An eighth inch off here and there makes it look BL and therefore removes the car from the surreal uncanny valley.
For instance, light at an oblique angle down the side of the car. By the seventies, the tooling and workers were well out of line so that's the best of British, right there.
The wing gap is to make it look sporty as if the entire front end flips up, like a sports car.