Hi Carol
I started a search today at the archives.
Just looking at 1750 to 1760 in Elsdon there were 4 Hall baptisms but none for Allan. Father's names were Thomas, Joseph, Michael and Edward Hall - could be connected. I also looked at Kirkwhelpington for the same time period - only one Hall baptism - William to father John.
It's the neighbouring parishes that I think you should be looking at - and possibly later than 1760. Netherwitton should possibly be next.
I also noticed that there were a few people with the surname Allen/Allan so wondered whether this could be a connection.
Christine