As Ben Miller makes his cameo, here's how DI Richard Poole returned to Death in Paradise

Having returned to Saint Marie after the attack on her mother Catherine Bordey (Elizabeth Bourgine), Camille (Sara Martins) is alone on the beach – and full of emotional torment about whether her mother will survive, whether she's neglected their relationship, and whether it's too late.

Then suddenly she's not alone: sitting next to her in a suit and tie is Richard Poole, dispensing wisdom and urging her to live in the present. But when she turns to face him, he is – of course – not actually there.

So how did the cameo come about? And why do it in this particular way?

"It was an organic conversation about: what do you do for the tenth year? What could we do?" executive producer Tim Key tells RadioTimes.com. "We had ideas of seeing Ben, and I didn’t want to speak to Ben until we had the right way into it. And I also knew that if we got Ben, it would be very brief, because he’s a busy guy."

So the team began thinking of ways for Miller's character to appear from beyond the grave.

Death in Paradise creator Robert Thorogood recalls a meeting with Tim: "I think that you said, 'Could he come back as a ghost?' and I just went, 'That is brilliant. We are doing that.' I remember the rest of the room were a little bit sceptical. They were like, 'But ghosts don’t exist.'"

"It was sort of a joke," says Key.

But it was also a serious suggestion. The only other contender was an episode based on flashbacks – and that had its own set of challenges and issues: "Do we talk to Gary Carr [DS Fidel Best]? Do we see what we could do? Do you get everybody back and do the whole team, flashing back through an episode? We knocked that, a) because logistically we thought it would be very difficult, but b) it felt obvious. We also felt that was living in the past too much."

The "ghost" idea looked more and more appealing. "So then it became: could you do something where Sara imagines she was chatting with Ben?"

Miller came on board, and said yes – immediately. Martins was also delighted to return to the Death in Paradise cast as a guest star for the double bill. So then it became a matter of getting the scene just right.

"We approached it, again, like we always do, with our own set of rules," Key explains. "She never looks at him during the entire scene. It’s not like he’s literally a ghost. He’s just there in her head.

"And the dialogue was very, very carefully judged to be sort of knowing without being too on the nose. He sort of tells her that he loves her, which is the moment that a lot of people – you always knew that he was sort of falling for her, and he sort of tells her that he loves her. But he doesn’t tell her that he loves her. He’s telling her to go tell her mum that she loves her.

"I really love that scene. We were very careful about where we put music on it – and when she does turn, he’s not there... and it’s set up earlier in the episode that she kind of imagines herself speaking to him. She says to her mum, 'He’s sort of always there in my head, and I can imagine what he’d say to this.'"

Reflecting on the cameo, the executive producer tells us: "I think it’s a really lovely moment... it does respect the past. It’s lovely to see them together again. But I don’t think it outstays its welcome. It’s a moment in an episode. It’s a really sweet moment. And then the episode moves on – as does the show."

Thorogood adds: "It’s magical... he’s there, and then he’s not there. As Tim says, of course he’s not a ghost, because ghosts aren’t real, so you have to try and address that. But we deliver all of the joy that a ghost might be able to give you."

The scene itself was quite a feat to pull off.

"We thought when COVID struck – we just assumed that was the thing we were probably going to have to cut," Key says. "That was a complication that we could probably do without. But all of us were determined to try to make it happen. And so was Ben. I thought Ben might just go, 'Nah, it’s too much. I can’t do it.' But Ben really wanted to do it. He was so up for it."

But with all the willingness in the world, Miller only had a window of two days to film the cameo between finishing up on Bridgerton (in which he played Lord Featherington) and starting work on Professor T. And the episode he was meant to be in hadn't even started filming yet.

So, as Key explains, "We had to get him and Sara out there to do that scene, and then Sara came back out to do the rest of the episode around it at a later date." It was certainly a flying visit to Guadeloupe.

And while the audience now gets to reunite with Miller, the actor had a reunion of his own – with the suit and briefcase he left behind seven years ago.

"We still had them in storage," Key reveals. "Ben couldn’t believe it. He’s got his shirts that are adapted to have the back exposed. Yeah, it’s the exact, literal same suit. We didn’t even know we still had it, and then we found it. We found it – and there it was. And he still fit in it as well!"

Death in Paradise continues on Thursdays at 9pm on BBC One. Take a look at what else is on with our TV guide.