I found a baptism listing for a JOhn Furlong for 1744 and another for 1758, so either of them could be his. When I go to England again I am going to visit the East of London Family History Society where all the parish records for the churches in Middlesex are kept. I was also going to visit the graveyard of St Paul Shadwell to see if John has a gravestone and what is written on it, it could mention his children. The other thing I intend to do is visit a Mormon Church, apparently most Family History Centres are located in the church buildings.There are loads of them all over England. The Mormons have access to 2.5 million microfilms of Family History. Unfortunately I will not be going to England again until next year, it is a costly business travelling from Australia.
If I find anything else before then I will contact you.