Potterlore: JK Rowling explains the Dursleys as Dudley turns 35

Even the despicables have a birthday. On the occasion of Harry Potter's cousin Dudley Dursely turning 35, author JK Rowling has let out some more trivia for Potter fans.

Writing on her Pottermore fan website, Rowling explains in The Cupboard Under The Stairs extract the making of Vernon and Petunia Dursley, Harry's uncle and aunt; and what went wrong in the relationship between the sisters Lily and Petunia.

"'Vernon' is simply a name I never much cared for. 'Petunia' is the name that I always gave unpleasant female characters in games of make believe I played with my sister Di," she wrote.

The surname however was something she liked the sound of and borrowed it from the Gloucestershire town of Dursley.

She further wrote in the extract: "I have never visited Dursley, and I am sure it is full of charming people."

Petunia does not invite Lily to be a bridesmaid at her wedding, fearing her witching abilities. There is no further contact between them until a note informing the Dursleys of Harry's birth, which Petunia promptly bins, The Telegraph reported.

Tracing the first meeting between Harry's parents and the Dursleys, the extract describes how Vernon patronises James, who in turn is amused by his future brother-in-law.

A conversation about wizards ends up in Vernon storming out when James explains the working of the wizard bank Gringotts, owned and operated by the Goblins, and protected by winding passages and enchantments and creatures.

It is from these high-security vaults deep underground that the Philosopher's Stone and Horcruxes are stolen later.

Dursely's dislike of Harry stems from his resemblance to his father, much as it was with Severus Snape, who had shared a history with James.

Rowling toyed with the idea of redeeming aunt Petunia in the final book, but decided against and left Petunia indifferent to Harry during their final goodbye.

And so the saga continues, with extracts filling in and keeping the story alive. Until the next entry.