Jack,
I have just seen on C1851 (2418-132-10) in Mitford, the family headed by the Mitford-born JOHN JOHNSON and wife Mary.
His 19 yr old son, JOHN, a farm labourer, is recorded as been born in WOODHORN ( near modern-day Ashington)
On Census 1861, ( 3740-38-35) the JOHN JOHNSON who married Margaret Potts, is recorded as a Blacksmith and as been born in SEATON DELAVAL.
And on C1851 ( 2402-426-29) in Low Fell Gateshead, John, the son of John and Martha Johnson is a 20 yr old Blacksmith, born in Northumberland ( the Gateshead enumerator only recorded birth-counties, not birth-places.
So if you believe me, there are two candidates for the JOHN JOHNSON who married Margaret Potts..... in Gateshead in 1858, and was 30yr old and a blacksmith and born Seaton Delaval on C1861 (3740-38-35)..
No.1. The farm labourer, 19 yrs on C1851, born Woodhorn, living in Mitford, Northumberland in 1851, son of John/Mary.
No.2. The blacksmith, 20 yrs on C1851, born Northumberland, son of John/Martha, living in Low Fell Gateshead in 1851.
Over to you,
Michael Dixon, with apologies.