In 1998 and 1999 Joanne Rowling gave interviews with STV following the successes of her early Harry Potter novels.

This year marks the 20th anniversary of the publication of the first book, Harry Potter and the Philosopher's Stone, with various events and releases marking the milestone.

Her creation is widely regarded as one of Britain's biggest entertainment exports with the novels gaining new life on the big screen and in continuing merchandising.

Even at an early stage when writing the first book in an Edinburgh cafe, Rowling had no idea of the impending success her creation would bring.

In 2004, she was named by the Guinness World Records as the world's first "billion-dollar author".

During an interview in 1998 with STV she said: "It's completely surpassed my wildest fantasies, and you do have wild fantasies when you're writing a book.

"But I certainly never expected this kind of success - particularly the numbers in which people are buying the second book. I was stunned. It's only been out for a few days.

"I can only put it down to the fact there are a number of children out there - and possibly adults, I've met adults who are queued up and unashamedly asked for signatures for themselves... I think they just wanted to know what happens next so there's really no higher accolade.

"Obviously they love the first book enough to want to buy the second immediately, it's been wonderful."

Nor did she realise the writing block she would soon face as mounting pressure began to play on her mind.

Rowling added: "This has all come as a huge, enormous shock but my realistic side had not allowed me to dream of half of what has happened to me.

"It scared the hell out of me, truthfully. I was halfway through the second book and I became blocked and panic-stricken that I became very self-conscious of what I was writing."

But in 1999 she spoke to STV again and said: "I got my act together again, finally, but I was very panicked for a while.

"I never thought what I was writing was commercial, that's the truth of the matter. I just thought this was like my private little world."

And it's a sentiment which remains to this day, when the author tweeted a thank-you message to her millions of Twitter followers and fans.

Before long the inevitable trail of producers came calling while preparations were being made for the subsequent follow-ups to the novels.

In the 1999 interview she also stated: "I was in the unbelievable position of several people wanting to either make a television series or a film. So I did have a choice.

"And if I had felt uneasy about it I wouldn't have sold the character or the rights to anybody, truthfully.

"I do believe if they do everything they say they're going to do, it will be a good film."

The seven books eventually went on to spawn eight movies, making stars out of several young British actors, as well garnering a worldwide cinema audience on a similar scale to the novels' readership.

Rowling maintained her relationship with the characters throughout the filming process, while several Scottish landmarks that inspired some of her work have also received a boost.

A Harry Potter holiday tour allowing fans to see Scottish locations linked to the books and films has been launched to mark the 20th anniversary.