Zoe,
It's easier to list the ones that do than don't. Tag, Gama, Bookajet, Hangar8, Twinjet, LEA, Ocean Sky (Hell, they even have a decent handling agent) and pretty much every other UK based jet operator brand their aircraft in some way - be it in small "operated by xxx" letters by the door, safety cards printed on company headed paper or otherwise. Why on earth shouldn't they?