The November London Centre event – “It started with a book” – examined how books are adapted for the telly, drawing lessons from three very different projects.

The Hank Zipzer books for children – written by Henry Winkler, who played the Fonz in vintage US sitcom Happy Days – have been turned into a returning CBBC series.

Walker Productions Managing Director Helen McAleer, who had seen Winkler play Captain Hook in pantomime, was determined to make a version with the actor.

In the series, which is relocated from the US to Britain, Winkler takes a key role as the favourite teacher of Hank, who struggles with dyslexia. Much of what the main character goes through in the books is internal, so more was made of the other characters for the TV series.

JK Rowling’s The Casual Vacancy, which has 37 main characters in a chunky novel, presented a different set of problems.

Yet, the BBC One adaptation, which aired last year, ran to just three 60-minute episodes.

“It’s a convoluted story with not much plot – it’s very much about the characters,” said producer Ruth Kenley-Letts from Bronte Film and Television.

Screenwriter Sarah Phelps saw it as a 19th-century industrial novel, examining how cruel small communities can be.

Two French films, Jean de Florette and Manon des Sources, were in her mind when she was writing the script.

“All that raw hurt and a series of heartbreaking events, when just a little kindness could have made a big difference,” she said.

Explaining her approach to adapting Rowling's novel, Phelps added: “It’s about asking what is the beating heart of the novel – and remaining true to its spirit, rather than sticking to the letter of the text.”

Treasure Island has been adapted many times, and Kindle Entertainment ­Co-­director Melanie Stokes said it was important to make her company’s 2012 version for Sky 1 resonate with a modern audience.

“I wanted to draw a parallel with the banking crisis – that period of unbridled greed – and it’s why we cast Squire Trelawney as not just a buffoon, as he is in the book, but as a very selfish character,” she said.

“It’s remaining true to Robert Louis Stevenson, but making the story relevant to a modern audience.”

The casting, Stokes argued, was key – and none more so than Eddie Izzard as Long John Silver. “He’s mercurial and felt absolutely right for the part,” she added.