aslong as the harness is secure, its not an MOT failure, ive had a few cars through with harnesses.
but i did goto a strict strict garage!
Thats not true mate.
Garages all comply to the same vosa mot guide handbook.
And that is purely down to the tester as an individual how they are interperated.
As for harnesses make sure that they are fitted correctly,securely and fasten, release as intended.
if for some reason you have left the original seatbelt in also leave the, clasp/receptical/buckel/stalk retainer etc as a belt without is a fail.