Catherine Tate is shocked by the success of ‘Doctor Who’ in America.

Catherine Tate is very surprised by Doctor Who's reach in the US

Catherine Tate is very surprised by Doctor Who's reach in the US

The 53-year-old comedienne first appeared on the BBC sci-fi series as the titular character's assistant Donna in the 2006 Christmas Special and went on to appear in the role throughout the fourth series but had no clue that the show “had a big audience” across the pond but feels as if it is still "pretty niche" when compared to Hollywood blockbusters.

She told Daily Star newspaper: “They’re enormous fun. I didn’t realise it had a big audience in America.

“Compared to the Marvel films franchise though it’s pretty niche.”

The sketch show legend admitted that while she loves the show so much - which has had 14 people assume the title role, including Tom Baker,89, Matt Smith, 40, Jodie Whittaker, 41, and the upcoming star Ncuti Gatwa, 30 - but not in the same way that two-time Time Lord David Tennant, 52, is a "fan".

She said: “I must make full declaration - I don’t know anything about ‘Doctor Who’.

“I love it and I love being in it but I’m not the fan that David Tennant is.”

The former 'US Office' star is to return to the show alongside David Tennant for a three-episode stint as part of the series' 60th anniversary celebrations later this year and confessed that the on-set tech “has come up a pace” from her original stint on the show/.

She said: “We worked in a green studio, and it has come up a pace from when David and I had been on it before, I can tell you that.

“The budget and the scale and the studio have all increased.

“Genuinely it used to be a tennis ball on a stick. And the director would say, ‘That’s a monster.’

“Now the tennis balls and sticks are much bigger - they’re absolutely enormous now.”