Aside from the P in a circle, which is, as correctly stated, a prototype marking, on the MZC 01, both those aircrafts show RAF roundels. It's difficult to spot at a first glance, but the grey scales denote a darker external circle outside of the white one in regards to the one inside, while on a French roundel it would be the exact opposite.
Eg.
RAF Spitfires:
French Air Force P-47, F8F, A-26:
Moreover the flags on the keel of both aircrafts have a middle white rectangle which is smaller than the blue and red ones, as typical of RAF markings and opposed to French ones, where all rectangles are of the same size.
That said, i'd be more keen on thinking these are just fantasy artworks, and there are several things that make me think so.
Aside from the technicalities, one of them is the fact that on MZC 01, while all markings seem to depict a British aircraft, the flag on the tail has inverted colors: it should be red first, then white and blue towards the rear.
Another one, is the fact that on MZC 02 there is no visible intake for the jet engine too.
I doubt that one familiar with the what he/she's depicting, could do similar mistakes.
Moreover "MZC" gives me more the feeling to be the signature of an artist rather than something correlated to a designation system.
So, while they're indeed both impressive looking designs, i'd say it's just fantasy artwork though.
Regards.