I'm still not totally clear as to what this certificate you're calling a 'PartP' actually is - is it an Electrical Installation Certificate or a Building Regulations Compliance Certificate?It means the PartP does not comply with the Law in that the sparks who issued it did not do the work, nor did his firm. He is a 3rd party and just did the sign off. On the back of the PartP Cert it says ...
Kind Regards, John
Part P of the BR