That MOT man needs a serious talking too
Nothing there that's Advisory ?
As for not losing these covers
Take a small zip tie and secure the uppermost clip to the mesh
If you are careful you can barely see it
Then if you hit a bump it may jump free BUT you won't lose it
I have done this on my car after I lost a cover
You cannot even see them on the photo below
The bonus is you can flick the mesh out for cleaning and just clip it straight back
Sorted