St Oswalds only has marriage records dating back to 1954. For earlier information on births, deaths and marriages, visit http://www.shropshire.gov.uk/archives
Oswestry Family and Local History Group has a treasure trove of useful and fascinating material https://www.oswestrygenealogy.org.uk/
Shropshire Archives has a good service for family historians, and there is free access to Find my Past at the local library.
The archives may be phoned on 01743 255350 or contacted by email at firstname.lastname@example.org