I'm pretty certain this is bits of Inoceramus ( a large bivalve), at least from what i can make out in the photos.
I doesn't look like bone to me, but its definitely fragments of a fossil.
It is quite possible find bone on flint, but i should say that would be an extremely rare find, & i have only ever seen a few examples myself, mainly fish bones.
I think this is the discussion that Thomas was talking about.
I agree with Keith, I don't think it would be possible to give any more info than he has.
Keith - I've never actually seen bones in flint, very rare as you say - do you know where I could see any pictures? I might ask my colleagues in the palaeo department if they have any examples to show me.
Here's a link to a fish in flint that a member of another forum posted some years ago,
Other than that i have seen one reptile tooth & the odd shark tooth in flint, all found around Europe & i remember reading a newspaper artical about a fish skull in flint found along the south coast of England (about 4or 5years ago).
I would love to know what examples you can find in the museum.
The same member also posted a possible gastrolith with an association of fish scales around it, its somewhere on the archived forum but I can't find it at the moment - it is an interesting example of fish bones in flint though.