Velile Tshabalala as RositaIn this year's Doctor Who Christmas special, the Doctor is set to meet up with erm, the Doctor and a new companion.

We caught up with the 'other' Doctor's assistant, Velile Tshabalala to get some insider info on the upcoming episode.

What can you tell us about the episode - The Next Doctor?
The Doctor arrives in Victorian London in 1851 and he comes into contact with another Doctor - played by David Morrissey - and his assistant Rosita, played by me. I still get really excited when I say that!

What's Rosita like?
She's really cool; she's great fun to play. She's quite like me - a mouthy cockney girl! She's really feisty, she gives as good as she gets. She's got loads of admiration for her Doctor.

When we meet Rosita she's dressed in a Victorian outfit - does she belong in that time?
Yes, that's her home. It's not made clear where she's travelled to before though.

What's her relationship with the 'other' Doctor?
She's been his companion for a while, it's clear they've been together for a long time.

What about her relationship with David Tennant's Doctor?
She doesn't really know what to make of him. She doesn't really trust him and she's quite cocky towards him at first. As the episode goes on, a lot of stuff is revealed and the relationship changes.

What about the dynamic between the two Doctors?
It's brilliant, it works really well. David T plays the Doctor very quirky,and can be quite sarky sometimes. But David M is more suave and charming, a real English gentleman. The way they bounce off each other is fantastic.

Obviously, there's a bit of competitiveness between the characters at first. You know what men are like...

What was it like to step in to the Tardis?
My character doesn't go into the Tardis, but I snuck in when no one was looking! It was like being a kid in a toy shop – just fantastic.

Tell us about the baddies...
Dervla (Kirwan) is fantastic as Miss Hartigan - like a beautiful, icy snow queen. She's working with the Cybermen, they're like her army.

There's also a new type of Cyberman...
They're interesting, neither Doctor has encountered the Cybershade before so it's something different for them to battle.

Has the door been left open for a return?
I would love to be part of this again, but in terms of coming back you'll have to wait and see what happens to my character I'm afraid...

You can't tell us anything?
No! I'm sorry I feel really horrible!

What was the Doctor Who experience like for you?
It was daunting working with such big people, but at the same time it was a great honour and I learned a lot from them. They've been in the business for a long time and they're all really talented so it's great to have that inspiration.

What attracted you to the part?
I have to admit, I'm not the biggest Doctor Who fan but I do always watch the Christmas episodes so that was one thing that really stuck out for me. I love the character of Rosita, and the chance to work with such great people was a fantastic experience.

David Tennant recently announced he's decided to leave the show, could David Morrissey take his place?
I think so - but that's easy for me to say! I think he's brilliant; he'd make a great Doctor.

Well, we'll just have to wait until Christmas Day to find out if Velile's right. In the meantime check out what's in store with our spoiler pics of The Next Doctor Xmas picture gallery.

Velile stars as Rosita in the Doctor Who Christmas special: The Next Doctor, Christmas Day on BBC One.

Find out when Dr Who is showing on TV.