To save some bother I have the church marriage entry, I thought you must have had the certificate from what you were saying.
They married at Brooms, a church now in the middle of nowhere near Leadgate.
30th September 1858 (In Latin which I have changed to English)
Francis Keoghan of Berry Edge son of Daniel Keoghan
and
Mary Doran of Blackhill daughter of Edward Doran
witnessed by: Michael Marrin of Berry Edge and Margaret Carolan of Berry Edge.
Berry Edge was the old name for Consett which in 1858 was within the newly founded Catholic parish of St Mary's, Black Hill which was yet to to have a licence to perform marriages so that is why they would have had to go to Brooms, however the baptism of the child will be at St Mary's, Black Hill and those registers are at the Durham County Record Office too, but you normally need an appointment in advance to book a micro film reader.
Good luck,
J.T.A.