It's pretty standard for Doctor Who's lead actor to tweak their performance across their time on the series, as they grow more comfortable in the part and their understanding of it grows... but perhaps no Doctor changed more than the seventh, played by Sylvester McCoy.
More of a clownish figure in his earliest episodes, McCoy's Time Lord evolved into a darker, more cunning figure as his era went on.
Speaking to RadioTimes.com about his Doctor's transformation, McCoy said, "Every season, we’d all get together at the beginning, and we’d chat about what we wanted to do for the next season. [The change] was a personal thing, really.
"My grandmother had got to be 100 years old, and I went to visit her in the early ‘80s. And that was not common, to have 100-year-old people around...
"She was as sharp as a button. But there was a sadness and a weariness [about her]. She’d seen so many things. She’d lost children and grandchildren. She was born in the Crimean War, and she’d been through all these wars.
"And I thought, 'Wow, I want to bring all that baggage to my Doctor.' So that’s where that darker side came from."
On reflection, McCoy wishes he'd played up this darker side to his Doctor earlier. "I was very ignorant," he said. "When I got the role – not having seen Doctor Who, I had no idea. It was like any role. The producer said, 'OK, there’s the script. Get on with it. That’s the key to the TARDIS. On you go.'
"So I arrived with my bag of tricks. So it was slightly comedic, and I fell over a lot."
This more light-hearted slant, and one gimmick in particular, was encouraged by then-producer John Nathan-Turner, McCoy insisted. "He used to like having a party when we were on location – and Bonnie Langford [companion Mel] did a party piece, and sang amazingly.
"So I got my pathetic spoons out and played them. And he said, 'We’ve got to have that in Doctor Who!' – I thought he was joking, and then the script arrived the next day, and there they are!"
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Doctor Who was put on 'permanent hiatus' in 1989, with the evolution of McCoy's Doctor cut short. Prior to the cancellation, he'd had conversations with script editor Andrew Cartmel about where his Doctor might go in future, and some of the revelations that were planned.
"It was like taking the onion and peeling off the skin, and underneath there was something else," McCoy explained. "The idea was that perhaps we wouldn’t actually tell this story, but we’d hint that there was more to the Doctor.
"There was a great mystery and a greater strength, and the idea that perhaps he was one of the triumvirate that had founded the Gallifreyan society – [like] the Father, Son and the Holy Ghost."
These concepts would later be explored in a series of Doctor Who novels published in the 1990s, while the show itself eventually returned to screens for a TV movie in 1996 and a fully-fledged series in 2005.