A neighbour of my mates just had a two sockets fitted outside, one near lawn and other near water feature to replace the unsafe extension lead previously there. Fitted non DIY (from what I understand) using SWA cable to separate mini CU in garage, I peered over fence all looked terminated OK from what I could see and cable buried underground in either gravel gap round house and under flower bed.
But my mate in chatting to neighbour about this, and possibly wanting the same, neighbour completely unaware of any BCO / Part P requirements, though installer did mention something or other, but he's not too sure. Neighbour not bothered, going to stay in house till he dies, happy it all works.
So has part P made any difference in the field................
Actually my mate had a good one in the house he moved into, 2.5mm white T&E existing through hacked hole in side of double socket in his conservatory, up wall, through "hacked" hole in polycarbonate roof, back down outside wall to water proof socket. All holes smeared with masses of silicone sealant !!! This has since been changed !!!