“Exquisite. Absolutely exquisite.”

"And since it has no call to be here, the art lies in the fact that it is here."
"Exquisite. Absolutely exquisite."

Many of you will recognise these words as precisely one half of the lines spoken by John Cleese and Eleanor Bron during their brief comic cameo in 1979's City of Death. Blink and you'll miss them. (Whatever you do, don't blink.) And that's the point of their casting. They have no call to be there, so the art lies in the fact that they are there.

It's called a cameo. Doctor Who didn't really do cameos, historically speaking. Maybe Hale and Pace. More recently, we've seen everyone from McFly to Patrick Moore show up. But a cameo's just a bit of fun, really, and we take it for what it is.

More bizarre is the phenomenon of"stunt casting". I don't know the earliest example, but it doesn't really kick in until the 80s anyway. I'd define it as a piece of casting purely to generate attention. So not Richard Todd, Martin Jarvis or even Beryl Reid. But how about Paul Darrow? Or Alexei Sayle? Or Michael Sheard in Remembrance of the Bronson? Or Frank Windsor in Ghost Light?

Or Ken Dodd?

21st century Who has many examples of stunt casting. It's hard to draw the line between simply casting a name (Simon Pegg, John Barrowman, Pauline Collins, Maureen Lipman) and pure stunt casting - but perhaps Peter Kay starts it. I seem to remember Radio 1 heavily trailing Love & Monsters on the basis of its guest star, which certainly didn't happen for Roger Lloyd Pack.

And then there was Catherine Tate, popping up in the TARDIS at a point in her career when her sheer presence was enough to crown an entire series finale. Following this success, there are many more examples: Kylie Minogue, Michelle Ryan, James Corden, Katherine Jenkins.

But the story immediately following Donna's maiden outing, Smith And Jones, also began a curious other type of casting, which I shall here dub non-stunt casting. It's like this: why on earth shell out cash for an established star like Roy Marsden to play a three-scene character who dies after 15 minutes?

Over time, this has become increasingly apparent. What was June Whitfield doing in The End of Time? How can The Eleventh Hour throw away Annette Crosbie, Olivia Colman AND Nina Wadia on tiny non-roles? Bill Nighy, Michael Sheen, Lynda Baron - all actors whose casting seems out of proportion. It reminds me of JNT trying to get Laurence Olivier to play the mutant in Revelation of the Daleks.

The last Christmas Special went all out. Not satisfied with hiring top sitcom star Claire Skinner, the Moff writes a couple of brief, slightly comic, superfluous roles then casts Bill Bailey and Arabella Weir. And to rub it in, the third, equally featured, equally comic spaceman is played by Some Bloke. They arrive, we cheer, then 5 minutes later they've gone.

Oh, and. The husband, who gets a handful of lines and is a mere plot device and could have been successfully portrayed by Ed Wood's dentist, is played by Alexander Armstrong. Comedian, Pointless host and bona fide Doctor Who legend thanks to his role voicing Mr Smith in The Sarah Jane Adventures. Why?

I get the fun in stunt casting, but why distract us by throwing stars like Armstrong and Wadia into roles which waste them? It's like the thirty seconds George Clooney spends in Terence Malick's The Thin Red Line: all I remember is his unexpected appearance, nothing about his role.

These name actors have no call to be there. Exquisite? More bizarre, I'd say.