Frame Identity Challenge!

[Mikb23]

Can anyone please identify what frame this is is? I'm getting nowhere and it's doing my head in! It says Plum on the down tube but not sure if that's original. The rest of the bike is mid-spec'. SRAM SX-5/Blaze, Manitou Splice Comp 130's, WTB components/Hayes Sole brakes.

I don't have any frame serial no I'm afraid.

Help!