Just looking through our family tree that has been put online by my sister - I think the earliest we have been able to go back is to the birth of one Daniel Pearce in 1657 in Gloucestershire. He is my 8 times great grandfather. His wife was Edith (born around 1661) but we don't know her maiden name. This is on my mother's side.
On my father's side I think the furthest we have gone back is to Edmund Holmes who was 25 years old when he married Rose Rivett aged 21 in 1730 (Norfolk, England). They were my 6 x great grandparents.
The furthest we have got back in Scotland is 1772, and the furthest back in Ireland is 1790.