My guess would be that the original vent hole has been blocked and the bit you refer to is a homemade inlet, having a peak to stop the water getting in........if you look closely it has 3 holes in the front, presumeably to let air in
Either that or it's a James Bond style mini rocket launcher!!!
Black and white plates would suggest that it's tax exempt. It would be well worth an email to the seller to ask for the Chassis number underneath the engine lid
Assuming PGJ is the same locale as PGY it's likely that this one was supplied by the same dealer who sold Peggy. If, and it's a big if, the local DVLA office issued new registrations in order then this one would have been registered before Peggy so as Peggy is Tax-free this one could well be.
I am not a person, I am a number, 395 actually......Be seeing you!
If I told you I was a pathological liar, would you believe me?