isn't there an issue with painting the topside of the aircraft any colour other than white anyway because of the heat generated in the cabin?
in which case we're talking about different colour greys for the underside of three aircraft, which, lets face it, aren't likely to be on regular display at airshows - a mighty 'meh' is the reaction from this callsign..
£3million buys a lot of fuel for a reinforcement exercise down south, or an AAR kit for a C-130J (ok, it goes towards an AAR kit for a C-130J..) all of which contribute far more to Defence than buggering about with colour schemes.