Two different books: John Hamlin’s was published in 2003 and Colin Dodds in 2005.

The Hamlin book is more of a production list of the four types (five if you count the Dolphin). It does have an appendix of UK operators of the four types.

Colin’s book is much more narrative describing various aspects of operations of each type.

To my mind the books complement each other. Both have excellent photographic coverage with very few duplications. I bought them both………..!!!

Planemike