David Tennant almost missed out on Inside Man role

"Once I'd written the first couple, or maybe just the first one, and shown it to Sue [Vertue, producer], we both agreed that it'd be a perfect part for David Tennant, and we know David really well because we hang out with David and Georgia [Tennant] quite often, and obviously I'd worked with him before.

"We just thought he'd be perfect, but he wasn't at all available. His entire schedule was booked up, largely with theatre."

It was only after they had "gone around the houses looking for a Harry" that the COVID-19 pandemic began, shuttering theatres. "COVID closed the world down for two years and David was suddenly much more available," Moffat explained.

Though exact plot details are shrouded in secrecy, we do know that Inside Man also follows a prisoner on death row (Stanley Tucci) whose life becomes unexpectedly entangled with Tennant's vicar – and it was Vertue who suggested Tucci for the role of convicted murderer Jefferson Grieff.

"Sue having read the first two said, 'That's Stanley Tucci, that's just definitely him, there's no question, it's got to be him.' And other people kept raising other names and she said, 'No, it's Stanley Tucci, it definitely is.'"

Inside Man also reunites Moffat with Dracula star Dolly Wells, who here plays teacher Janice Fife and was the first actor cast.

"I'd been writing it in front of the monitors for Dracula, and once I got to the end of episode 3 and Dracula was finished filming, I remember just thinking, 'God, Dolly – it's Dolly, isn't it? Dolly should be Janice.'

"She'd been so great as Sister Agatha – such a fantastic, unknowable, off-kilter, funny, but quite moving performance. I thought, 'She can do it' – and you'd never quite know what Janice was thinking if Dolly plays it."

Inside Man airs on BBC One and BBC iPlayer on Monday 26th September at 9pm. Steven Moffat and Dolly Wells will also feature in the new behind-the-scenes podcast Obsessed With... Inside Man, available on BBC Sounds on 27th September.

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