how did you determine range of possible birth years for william - there is Jurby born Wm - bapt 1746 if the jurby igi is to be believed (I checked ballaugh bapts for some decades but hadn't got round to checking Jurby - many corlet entries I could not find in the 1911 transcription, one or two were misreadings of eg corkill as corlet, others had transcription errors in the date (best I found was one 40 years wrong in marriages)