According to Alan Stanley Blair of ScyFy Portal, it can finally be confirmed that Naoki Mori's character of Toshiko Sato on 'Torchwood' is the same Toshiko Sato as seen in the 'Doctor Who' two-parter "Aliens Of London" and "World War Three". (I hate those titles! I would've named those episodes "The Gas Exchange" and "Number 10 Downing".)
There had been some question about that because in 'Doctor Who', Tosh was an intern at Albion Hospital. But now that she's working for Torchwood, Owen Harper is the go-to guy for the medical work, while Tosh has been their computer geek.
According to Ms. Mori, "Yes. I cleared it with Russell T. Davies and he said yes. Actually, that gets referred to a lot later on in the second season of 'Torchwood' as well. You have to keep watching the second series of 'Torchwood.' There's a lot of things that get cleared up."
She makes mention of one such topic, but as I didn't understand it (and the link that led me to the story seemed to be something of a spoiler), I'm not going to reveal what she said. That's for the benefit of those of us here in the States unfortunate enough to see 'Torchwood' on a delayed basis......