US actress Sandra Dickinson voices Grandma Tracy in ITV’s long-awaited Thunderbirds Are Go, starting this Saturday. What’s On TV caught up with Sandra recently, who told us what to expect from the funky Tracy family matriarch and what Grandma keeps in her very space-age bum bag…

Were you familiar with the original 1960s Thunderbirds, with puppets on strings?
“I came to England in about 1969 when they were already doing the repeats, so I was very familiar with it. The world is far scarier now than it was then. Stephen Hawking said recently that the fear for him was mankind bringing itself down from its aggression. Our show is set in 2060, but it’s extremely optimistic, where people are trying to stop all that and help mankind survive. We’ve really embraced the original show and built on the love of it. The new version hasn’t tried to be really clever and make it something really new. It’s kept the original feel to it. It’s just delightful and lovely being part of the 50th anniversary embrace of an iconic show.”

So what’s Grandma Tracy like in Thunderbirds Are Go?
“Grandma is the matriarch of the family and very hands-on with organising stuff around Tracy Island. She now wears a bum bag – which was my idea – and it’s full of very practical things. I’ve often worn a bum bag – or a fanny pack as they’re known in the US – and although they’re really unfashionable now, it’s very practical for a person in space! There’s one scene where I’ve got all kinds of useful stuff in it, like a compass and a map.

“I think bum bags are so cool. I first started wearing them when I was on Broadway and I had a fear of being mugged when I came out of the theatre. It came from my childhood experiences of going to New York. My mother used to say: ‘If anyone chases you turn around kick him’. And I always knew where! Without asking.”

So how does Grandma relate to her grandsons, the famous Tracy brothers of International Rescue – Scott, John, Alan, Gordon and Virgil?
“She’s not a very good cook, at least the boys don’t think so, and they let her know about it! She thinks she’s a good cook and she’s always offering them her cookies. Grandma grows, in a hands-on strong-womanly way, as the series progresses. She’s very much part of the action and the family.”

How do the Thunderbirds Are Go characters compare to the original puppets?
“The one thing I’ve noticed is the eyes of the characters are extraordinary, almost otherworldly. I personally get made fun of a lot because I have white eyebrows, but Grandma Tracy also has them. So that’s quite nice. My voice is different from my usual tone. I read in an interview about me once that said I had a voice like the Radiophonic Workshop. Now I’m doing a lower-voiced character it’s going to surprise people.” 

We’ve seen you in plenty of sci-fi TV shows before… do you like the genre?
“I have a long history of sci-fi in my life, going back to The Hitchhikers Guide To The Galaxy in 1981. And it just carries on from generation to generation. I was married to Dr Who No 5 (Peter Davison) and my son-in-law is Dr Who No 10 (David Tennant) and now I just keep doing more and more sci-fi, so that’s quite fun.”

Do you pop along to many sci-fi conventions?
“I had a lost weekend once, with Mark Wing-Davy (Zaphod Beeblebrox) from Hitchhikers and my ex Doctor Who husband from Gallifrey when we were all somewhere in north-middle America. We were holed up in this suite of rooms in a hotel for a sci-fi convention. I haven’t done many, though.”

Thunderbirds Are Go premieres on Saturday, April 4, ITV, 5pm