Hi. It sounds like he was granted a discretionary visa which cover circumstances outside the immigration rules. I've heard if this before but you need a solicitor. Sounds like the man was an illegal but the solicitor would have made a good case and the Home office /UkBa would have known they could hardly deport someone with a wife and baby here because of Human rights legislation. This is partly why visit visas are hard to come by because so many in the past have come for a visit and never gone back and it's pretty hard to get rid of them if they've disappeared for quite a while and then established a life here.