This isn't your first brush with the genre, as you did Neil Gaiman's Neverwhere. Any particular memories of that?

The negative memory of it is that the BBC didn't spend enough money on it. If they had, I think it would had a bigger following.

The best memories of it really were just the great Neil Gaiman, and the fact that his imagination is just so fertile. He's a fun guy as well, but his imagination is just so fertile he could have written 50 episodes of that and still kept us thinking, 'Gosh'.

Also the great thing [was the idea of] using the stations of London - like Blackfriars was where all the black friars lived. Seven Sisters were seven evil, not to be trusted, sisters. Wonderful stuff, really clever stuff. At Knightsbridge, there was a Knight on a bridge, and you couldn't get past unless you defeated the knight. Now that kind of imagination was wonderful.