Tom's Sanitary towel

[P-Courty]

Mine failed on my rear alfa seats for same reason not secure in upright position yet they were on the peugeot brackets (granted adjusted a little to fit but still as solid as standards) with a steel bar that clicks into the little release hooks near the rear windows. I never found them unsecure or falling down/wobbling when i drove also had people in the back and they never thought they were unsecure and didn't fall into the boot on acceleration lol, in the end removed them, if they aren't there they can't be tested meaning they can't fail. m.o.t just stated "rear seats missing at time of test" and passed.

Going off that surely if your seat is in a secure upright position and can't be pushed up or down by hand then they should pass it.
The handle to adjust to another upright position can't be tested as it's not there so they can't fail anything considering the seat is secure in the position you have left it for the test.