A key question

I would P&A

However a refusal could be an option if the dual purpose vehicle was a 4X4 which needed decel brake testing and the tester was concerned that using the car on the road was dangerous if it was not possible to easily kill the ignition should the need arise

Yes

P&A I'd say, only ref to ignition key is in 2.1 Steering Control which says: b. remove the ignition key (if appropriate) .

That's if the tester considers it to be ba permanent alternative obviously...

Dual purpose because it carries passengers otherwise it wouldn't be a Class 4 test isn't it?...

pass and advise,assume it has a coded ignition-pretty much everything has these days and as such has a means of permanently disabling vehicle that could be accepted as a substitute,even ignoring the is it/aint it passenger vehicle garbage/standard fitment etc.about the only motors you are gonna fail on ignition lock fault are renaults and thats only because they keep malfunctioning/locking when not required.....chance of you failing ANYTHING on ignition lock missing are zero