I was interested to read your query because my ggfather, John McPaden/McPadden was living in Sunderland (10 Frances St., Tunstall) in 1877 when my gmother, Mary Ann, was born. I've noticed other McPs in Durham County.
Most McPaddens come from Inishmagrath parish, Co. Leitrim. My John was from nearby Tullynascreena, Killanummery Parish.
In 1881 Patrick and Stephen McPadden lived as boarders with a Clark family in Westoe, South Shields. Patrick Clark was born in Inishmagrath, and his wife, Mary Hannon, was b. in Killanummery.
And I have this baptism from St. Mary's RC Church, Sunderland:
19 Nov 1859
James McPaden of N. Hylton, s/o Miles McPaden of Co. Leitrim m. Susan McDermott of N. Hylton, d/o Patrick McDermott of Co. Leitrim.
Wit: Michael Kelly and Rose McDermott, both of N. Hylton