I have been tracing my Sharman ancestors and have got back to the mid 1700s in Sutton-cum-Duckmanton, Derbyshire. I know there is another strand of Sharmans in the vicinity which I suspect are related but have not yet found the link. I suspect a generation further back may provide the key.
From IGI - I have a Richard Sharman b 1741 and Isabell Booer b 1745 both born in Sutton-cum-Duckmanton. But these are submitted to the site by an individual so I am a bit dubious about the accuracy of the info.
From a lookup on the Sutton-cum-Duckmanton parish register - I have confirmation they married in 1766 but no baptism for either of them.
I have rechecked IGI and have a christening for a Richard Sharman on 1st November 1740 in Dronfield, father John Sharman with a film reference number. But I am unclear how much confidence to place on this information. I guess the fact that someone has transcribed it from a film provides more confidence that the data actually exists but I have no idea how accurate these transcriptions are.