Thanks Diamond Diva, I was being thick, I've found them now
When it originally aired, I read that it was cancelled after 2 series, but obviously not the case. I'm trying to download series 3 and record series 4. When I saw it in the TV listings I just assumed it was a repeat because BBC didn't announce it was a new series
No Diamond Diva, didn't spoil it at all, each episode had a bit of info as to what was coming, and some I could see the minute the characters were introduced.