Stewart,
maybe you can find more information here:
http://cp1237.com/puzzlebox/
http://www.cleverwood.com/about1.htm
http://www.am-wood.com/apr98/puzzle.html
http://www.go-star.com/antiquing/puzzleboxes.htm
http://www.themindblock.com/Puzzle_Boxes.html
Cheers, Uwe