Barbara,
Yes if you get the chance to visit Newcastle/Newcastle Central Library, take it!
But also try to get to Northumberland County Record Office, at Woodhorn, and
Berwick upon Tweed Record Office.
Reason being that as Bo suspected, Newcastle Library holdings for Berwick Parish
( Church of England), Holy Trinity, are transcriptions of transcriptions, in very brief form.
Whereas Woodhorn and Berwick offices will hold film of actual church registers.
Today I had a browse through Newcastle Library's holdings of Holy Trinity ( on fiche)
I saw baptisms for Andrew 13 Jan 1754, Robert Alder 17 June 1756,
Christian 23 May 1758 and Frances 10 June 1759.
The baptisms of Robert, Christian and Frances were annotated with abbreviations for
Dissenter.
So perhaps the other children were baptised in the relevant non-Church of England church/es ?
In fact it is possible that the baptisms of the four children above, although recorded* in
the Parish Church, were baptised in the appropriate "Dissenter" church.
* For reasons such as Poor Law requirements.
A George Alder was baptising several children in same era in Holy Trinity
So too was an Alexander Hogg.
Michael