He was baptised on 19 July 1789 at Manningford Bruce, the son of Edward Guley and Sarah [formerly Powell]. This does not agree too closely with his ages in the censuses, of 56 in 1851, 66 in 1861 and 77 in 1871 (he would be 61, 71 and 81 respectively). However, there was no other Isaac Guley living in Manningford Bruce, where Ann Susanna was married and he could have been mistaken as to when he was born. There were no other baptisms of any other children of Guley families either, between 1782 and 1787. Also his maternal grandfather would be called Isaac Powell, if this were the correct baptism. There appears to be little doubt.
Isaac Guley married Sarah Dunford at Manningford Bruce, after banns, on 30 October 1815. They were both of the parish and the witnesses were Seth Osland and Esther Hitchens .
Sarah was buried at Manningford Bruce 10 June 1836, aged 41.
In the 1841 census of Manningford Bruce, Isaac Guley was aged 45, George 25 and Phoebe 20, all agricultural labourers, with Elizabeth 11, Kate 8 and Thomas 6. All were born in the county.
In the 1851 census of Manningford Bruce, Isaac was a widower aged 56, an agricultural labourer, born at Manningford Bruce. With him were his children Phebe, aged 32 and Thomas, aged 15, both born at Manningford Bruce.
In the 1861 census of Manningford Bruce, Isaac was a widower, aged 66, a thatcher/hurdler, born at Manningford Bruce
In the 1871 census of Manningford Bruce, Isaac Guley was a boarder, aged 77, a pauper, born at Manningford Bruce, in the household of James Coles, a labourer aged 33, with his wife, Christiana aged 38 and children George aged 10 and Emma aged 5, all born at Manningford Bruce. Christiana is in fact Isaac's daughter.
Isaac Guley was buried at Manningford Bruce, 9 September 1872, aged 77 years.
The children of Isaac and Sarah were: