As is the way in TV-land, events move at a frantic pace and paparazzi pictures of the new Doctor filming on the streets of Cardiff have already been leaked to newspapers.

"I remember thinking that will probably happen, that we’ll probably start seeing snaps of them – Matt Smith and his new assistant, Karen Gillan – on street corners and wearing anoraks and having cups of tea between takes. I was nervous about how I’d feel about that," he says. "Of course you feel a little bit proprietorial but I’ve just been really excited to see that it’s going on.

"I remember what it felt like to be where Matt is now and it’s really exciting to be seeing someone else starting out on that journey again."

Despite beating Tom Baker to the title of ’Best Doctor Who’ by the fans of Doctor Who magazine, Tennant remains humble about attaining such an accolade. "It’s been an incredible, slightly surreal experience to finally be up there and be part of that," he says. "It’s something that I will be forever proud of."

Although he reveals that shooting the final scene wasn’t as emotional as he’d expected. Due to the series being filmed out of sequence, Tennant’s last day as the Doctor was actually spent on the set of the spin-off series, The Sarah Jane Adventures.

"The last line I said as the Doctor is half-way through an episode and it’s, ’You two, with me, spit spot’. They were the last words I uttered in the suit, so I guess it was robbed of any epic quality!" says Tennant laughing. "That was probably best because it was very emotional saying cheerio and filming the very, very final scene was very sad. If the scene had coincided with the actual final day, I’d have been in trouble. I was in a bit of trouble as it was, but I was all right, I kept a mildly stiff upper lip!"

Reflecting on his time as the Doctor, he says without question the most rewarding aspect has been the star-struck reaction of the show’s younger fans. "Quite often, when I meet kids, they don’t know what to say," he says. "They get a bit overwhelmed by it, which I remember is what it did to me. I remember how enthused I got by the worlds that Doctor Who took me to and how special it seemed. When you feel like you’re creating a similar world for a child and you see it reflected back because they don’t know how to express it or how to say it, that’s very special."

But is it as special as finding your face plastered on an array of merchandising items? For when it comes to a series as popular as Doctor Who, there are the requisite off-shoots, such as Doctor Who bath bombs, Doctor Who lunch-boxes, Doctor Who cuff links, you name it, the Doctor’s face has probably been on it.

So what’s the strangest item Tennant’s seen his face on? "Pants," he says. "I think pants are probably the oddest, because they’re um... pants... I’m wearing some now!" he says, presumedly joking.

"Oh, and I do have some plastic action figures. I quite like having a plastic homunculus of myself. It’s a very odd thing and I’m not sure if it’s entirely healthy, but it’s quite fun!"