Why Every Lead Actor Left Doctor Who

Patrick Troughton reportedly thought that regeneration was a naff concept. "I didn’t think it was a particularly good idea of the BBC to replace Billy", he said. "I thought it was pretty silly, really."

However, he was eventually persuaded to take the leap – the consistent pay cheque no doubt played a role in that decision.

Like Hartnell, Troughton found Doctor Who's production schedule highly demanding. With dozens of episodes being produced per year, it's easy to see why! This is largely what influenced his decision to exit the role in 1969, with three seasons under his belt.

After he left, Troughton advised Fifth Doctor Peter Davison to also follow the three-year model, in an effort to avoid being typecast. Over the years, this has become something of an unwritten rule that many Doctors abide by, intentionally or not.