I paid a plumber and his apprentice an arm, a leg, two of my teeth, a kidney and my left knee cap for the removal of an old heating system and the installation of a new combi and ten new radiators. It took them both four days; not really full days either.
They did a top job though; no complaints; very professional, but I believe Corgi registered plumbers have to fork out about £2K a year just for their Corgi registration.