Details of William's birth are not known.

William married Mavis Lavender on Wednesday 20 August 1969.

He had the following children from his marriage to Mavis Lavender:

- Ian William Cockrill	born in 1972 at Ipswich.
- Ann Elizabeth Cockrill	born in 1974 at Aylesbury, Berkshire.
- Barry Edward Cockrill	born in 1978 at Ipswich.

Details of William's occupation are not known.