Hi Judy,
I know it has been several years since anyone posted on this thread but I wondered if you ever found the William Cumpstey' you were looking for as one has cropped up in my tree.
In the 1901 census, there were three Williams who were born between 1888-1894:
William Cumpstey 9 Lanc Chorley Lancaster Chorley Juvenile
William Cumpstey 9 Lancs Fulwood Lancaster Fulwood Juvenile
William E Cumpstey 11 Lancs Liverpool Liverpool C B Toxteth Park Juvenile
The second one who was living in Fulwood with his father John (a tallow chandler) and his wife Ada (nee Jones) is distantly related to me through the Jones family of Staffordshire. There were at least two other children: Percy who died after the battle of Somme, and John who married Gertrude Cowell.
Sound at all familiar?