How Desert Island Discs helped solve a Death in Paradise murder case

The quintessentially British radio show provided the clue that connected all the dots for Death in Paradise's DI Jack Mooney (Ardal O'Hanlon) and led him to the murderer.

And it all came down to the castaway's "luxury item": English breakfast tea.

Episode three introduced us to Frank O'Toole (James Faulkner), a prolific novelist and the writer of the bestselling Jim Harvey spy thrillers. But the morning after celebrating the 40th anniversary of his first publication with his agent, his wife and his research assistant, Frank went for a 5am swim. A couple of hours later he washed up with a knife in his chest. He'd been stabbed! At sea!

Puzzling over this unusual murder, Jack had a brainwave: he'd listen to the author's old episode of Desert Island Discs on iPlayer Radio.

"I love this show," he told DS Florence Cassell (Josephine Jobert). "It's a real institution back home. He has to choose eight records to take to a desert island!"

She wasn't impressed: "They leave him on an island? Alone?"

"No no no no no, it's not a real island," Jack explained. "It's hypothetical."

Still not convinced, Florence asked a perfectly valid question: "But if you're stranded on an island, why do you care about music? You just want to stay alive, no?"

"No, Florence. You're still not getting it," Jack said. "It's not a real island, it's just a way to get the person to reveal something of themselves. I was hoping it might give me some insight into Frank, but all it's told me so far is, he had woeful taste in music."

Having skipped over Frank's dire selection of music (a marching band!) he listened intently as the author revealed his "luxury item". "The one item I really couldn't live without is a decent cup of English breakfast tea," he declared.

What a bland answer! It seemed like useless information – but of course, in Death in Paradise, no detail is ever irrelevant.

Jack and his team were struggling to unlock the case. They knew that a mysterious man named Otis had bought and abandoned a boat, and the same man had rented a house on a neighbouring island. But who was he?

Opening and shutting the cupboards in the house "Otis" had rented, Jack found basic supplies: a few shirts, some biscuits, and... a box of English breakfast tea. The item Frank could never live without.

And then it clicked. Obviously! Frank had tried to fake his own death. He had planned to go swimming, jump on his boat, sail it to the rented house and live the rest of his life as "Otis". He would leave behind lots of false clues to raise his profile, everyone would presume he had drowned, and his book sales would soar. His wife would collect the money and, a few months later, follow on. They would spend the rest of their lives drinking the finest English breakfast tea money can buy.

Unfortunately for Frank/Otis, this daft plan failed even more badly than you'd think. The novelist was unwisely having a fling with his research assistant Gilly (Sian Gibson), who was obsessed with him – and when she overheard that he was planning to use and abandon her and take his wife with him, she flipped out.

So when he swam out to the boat, she was waiting with a big ole knife to stab him in the heart.

Case closed! Desert Island Discs saves the day.

Death in Paradise airs on Thursdays at 9pm on BBC1