Sarginson born in Perth, Australia but raised in Hemel Hempstead.
Krasniqi, born in Tirane, Albania but brought up in Feltham.
McMeeken, born in Basingstoke.
Clubb, born in Gravesend.

But they all came through the ranks at Harlequins/London Broncos, as well as a few others, Bryan, Caro, etc.
It shows that there is talent in the south if they are nurtured correctly, what a shame for the London club ( broncos/quins) that they couldn't develop a good solid, team around these guys.

Didn't Dom Peters pick up a drugs ban, or am I thinking of someone else?

I know he played for Lancashire in the Roses games, as the England selectors wanted to take a look at him playing at a higher level.

As Andy Gilder says Dom Peters recieved a ban due to drugs. Think the story was that took steroids to help improve his rehabilitation back from an injury.

Think you mean the Bolger brothers. They and others made it so far but were then either cut as not reaching the SL standard or could see they were not top of the list and sought other options. I believe both the Bolger brothers are or were in Abu Dhabi working as well as playing RL!

George Truelove returned to union, had a decent career in both pro and semi pro ranks I believe. Not really a London developed player tbh, was signed from Bedford RU from memory.

Off the top of my head.
McMeeken, LMS, Clubb, Sarginson, Caro, Dixon

Both Bolger brothers were involved with UAERL until it was shut down and banned by RU officials.