[Arran]

 Yes, I think it is a mahogany, I'm not sure what cut it is on that side though, crotch maybe? The other stuff looks like it's plain cut rather then quarter cut. It's not a walnut though, but I'm also not sure which species of mahogany it is, Honduras possibly, Brazilian maybe. Look up the various species of mahogany and see which one is closest, Constantine's used to have a gallery of different woods, if they don't someone else will. You might need to pick up some maple veneer for a underlying layer for parts of the cabinet as I can see that it's missing from some spots, the grain normally runs in the opposite direction of whatever is on top.
Regards
Arran