try The Dumbell Affair by Connery Chappell,
Prescot: Stephenson 1981 0-901314-21-8 gives bio + pics etc of Dumbells on island leading up to the back crash
try http://www.ee.surrey.ac.uk/Contrib/manx/people/printers/backw.htm
for backwells - would appreciate any additional info re this family