I want an 45 degree bend in rubber (28mm ID) with 200mm legs.

halfords do lengths of flexible hose - not sure if its as small as that. Basically, its got a spring inside, so it can be bent to any - almost - shape without it collapsing.

you could also try europa spares.

or, go to a kit show and see whats there. One this weekend at Newark.

atb

steve