High level brake light and bike rack

[HistoryBob]

I'm sure I read somewhere that it is illegal to cover the high level brake light. I.e. As when you load a bike onto the bike rack that hangs off the top of the door.
Has anyone else come across this? I suppose it could be a useful get out for the insurance companies should you have a rear end shunt.
The tow ball mounted racks don't have this problem.

 

[Les]

I did some digging on this once and evidently it is not a legal requirement to have a high level brake light but if one is fitted and connected it must work to pass the mot.