Hi Roger
Yes, as i was replying to you i was searching at the same time and when i saw mmn Harris i thought it is either she married another Harris or this is a child born out of wedlock and there is no fathers name given. I also thought your fathers name may contain a clue and had a quick look but decided to see if/what reply you would give, trouble is any info we found on that side of it could only ever be speculation, we need to try and find some hard evidence. I note you say your father was adopted, was this in Birmingham, you have to think there is a good chance that there is an adoption file regards this and there just might be information contained in it that will tell you more about his mother, not so sure about the father.
I would suggest you contact social services and make some enquiries with them, i don't know the rules and reg's but i would think that if there is a file, your father is deceased, and you can prove who you are you might get access to it, got to be worth a go.
bren