Thank you William - these notices confirm the approximate birth year for both Ebenezer and Margaret, which will help us narrow down our search for baptism records.
Also - have found out a bit more about Presbyterian marriages at the time.
There were some Presbyterian churches in Northumberland where the minister went to Scotland with the couple and performed the marriage there and then recorded it in the church record of the parish church in England. Given that there would be no marriage register, it is likely that the only one available to record the marriage would be the baptism one, which would explain this one of ours.
Certainly learning a lot about marriage customs and practice with this search - and I appreciate all the help you've been giving. Couldn't do it without you all
Catherine