It was suprising that Torchwood is clearly not just a half dozen or so guys and gals in Cardiff. As we saw in the latest episode of Doctor Who, they are a big organized operation. They manage to construct a super kill-o-zap ray in the middle of London for one thing. Ok, it's a bit like the Death Star in Star Wars as some fans have observed.
Source: The Christmas Invasion screen capture
If you listen to the commentary track available at the WHO official site, when RTD is asked about what Captain Jack's role will be in the show, he says Jack will be leader of the Cardiff branch of Torchwood only. So most probably the group we saw last night following the PM's orders is the London branch. Does it seem like Torchwood is just UNIT with a few more secrets?
Prime Minister Harriet Jones doesn't look like she will be around long enough to be on Torchwood as the rumours had it. The plotline that she both wasn't supposed to know about Torchwood, and also commands them seems a bit murky. Well, should be fun wading through all these new goodies for a few months anyway.