Robert, I can recommend to everyone, as has been mentioned elsewhere on the site, "Your Darley Ancestors", although it does have a distinctly American focus towards the latter part of the book.
"Henry" and "Thomas" will be names you will see again and again through the ages: even down to eg my father, grandfather and ggrandfather. Unless you have real specifics it will be impossible to work out which one was which! eg also The Reverends John Darley, of whom there were at least two or three, fathers and sons, all attended St John's College Oxford. Some Darleys went to America (one is famously depicted nearly succeeding in striking down an officer called George Washington (Colonel, not General) but was shot by the attending dutiful slave: his wound healed and he settled in the newly independent US instead) : some to Australia (one was Governor General of NSW). George Winn-Darley remains in situ in his family seat of Buttercrambe in Yorkshire. All this kind of stuff is from the book, "your Darley ancestors" but I don't have a copy to hand I'm afraid. My side of the gang came from Stoke Damerill in Plymouth, whilst my Gr-grandfather (Henry Cyril) moved to Kent around 1890 (I think).The family were successful boat builders in their time, near Ipswich and in Plymouth, and built the sister ship of the Mayflower, allegedly. Are you any relation of Bob Darley (Wateringbury, England)?