Hi Von
You could try the website
http://www.b4usearch.com/ if you click on the yellow word 'people' and enter his name in every combination you think he might be using.You also have to put a county,so be methodical and work your way though them all. It will take some time,but what else do you have to lose?
Alternately what address did you last have a definite siting of him? You might be able to get someone to look up the electoral rolls or local phone books from back then to a more recent time.Usually available at the local library.
Do you know if he remarried(I presume he is no longer married to your mum?)
He will obviously be easier to pin down if you know who he might be living with.
And my last option is Friends Reunited.
http://www.friendsreunited.co.uk/Good luck
Carol
PS I missed the 2nd page of this

so sorry if any of the questions are not relevant but some ideas here in any case.
