Hi just reread you post.
I have the children's Baptisms:
20 March 1836 Hannah Daughter of James & Sarah Metcalf, Barnard Castle, Weaver
3 March 1838 Martha daughter of James and Sarah Metcalf, Barnard Castle, Weaver
19 December 1839 William son of James and Sarah Metcalf, Barnard Castle, Weaver
12 December 1841 Mary daughher of James and Sarah Metcalf, Barnard Castle, Weaver
There are two possibilities for James' baptism, the first one is the most obvious, but I don't want to rule out the second, that's your call

15 December 1816 James son of James & Hannah Metcalf Barnard Castle, Tailor
4 September 1814 James & Susannah illegitimate living children of Mary Metcalf, Barnard Castle, Single woman
On other baptisms of children born to James and Hannah, there's some really good info:
1803: Mary Metcalf of Barnard Castle born June 16th baptaised Octr 9th 2nd daughter of James Metcalfe, Taylor, Native of Newcar (also spelled Nucar in one entry) Yorkshire by his wife Hannah Shield, Native of Auckham (also spelled Oakham and Ochum in different entries) Rutlandshire
There was also Elizabth born 23rd April, baptised October 19 (1806)
James born April 1st, baptised Dec 3rd (1809)
William born Sept 24th baptised Oct 13th (1811)
William baptised 10 October 1813
Hope this is helpful.
Anita