Complex sentence: For many years, St Etheldreda's church which dates from about 1250, was the oldest Roman Catholic church building in England, but the oldest building is now the church of Ss Leonard's & Mary's in Malton, North Yorkshire.
Split into simpler sentences: For many years, St Etheldreda's church, which dates from about 1250, was the oldest Roman Catholic church building in England. However, the oldest building is now the church of Ss Leonard's & Mary's in Malton, North Yorkshire.