Brake light test ignition off

Hi guys, hope you can help me. I have a ford ranger 2013 Pickup, all my brake lights work fine with the ignition key on, but with key removed only 1 works, which is an aftermarket light fitted into a hardtop canopy ( i know he wired it through a relay and connected direct to battery)
So my questions are a) do I actually have a fault at all, and this is normal for this make/model. b) I have a fault but it is not a requirement for an MOT ie, same as parking light I think. c ) yes I have a fault and brake lights are required to work even with ignition off and is tested for via an MOT.

many thanks Guys

Chris