Yes Bolitho is a common Cornish name. Must have been a lot of big bellies there. As far as I know there are no "little bellies".
I sang at a Cornish festival here in Australia a few weeks back to an audience of about 100 or so people of Cornish descent. In introducing a song I said, "hands up who hasn't got a Walter Bolitho somewhere on their family tree?" and 5 people put up their hands. We're all cousins of some sort. Joy