FamilySearch has a few possible baptisms for William Wellings around Ellerdine; could any of these be your man ?
William Wellings baptisms:
21st October 1787 Cressage, Shropshire
Parents William Wellings, Mary
21st September 1788 Great Bolas, Shropshire
Parent Ann Wellings
4th August 1782 Shawbury, Shropshire
parents John Wellings, Susanna
Regards,
Maurice