I have William Blease's in my family, - all from around Witton and Barnton. I haven't done anything much on that side of the family as yet, only that my oldest William Blease born in 1740 and was my 5th great grandfather.
I just had a quick look however in some preliminary notes of mine and the only William Blease that I could find that had died in Northwich around the time that you're looking for was one in 1904, at the age of 35 years. There was another who died in 1904 at the age of 47, but that was in Bucklow. Have you tried there? I expect that you already have his death certificate which hopefully states his age. I'm going away tomorrow for a week, but will check on this thread when I get back to see how you've got on and to see if I can find anything else to help you.