Another 'does anyone remember this book'? thread

[Fingerbobs]

This was a book I got (repeatedly) from the library. It was a hardback, perhaps Collins Children's Library or something of that sort, and I think the cover was burgundy. It was an historical novel about the child bride of an English king - Richard II, perhaps? I think she was called Isabelle? and was French? I remember her being on a ship, and being about 7ish when the book started.
Any clues?