As her publicity tour pulled into Edinburgh's Waverley Station last night, the multi-millionairess used a blonde decoy to get away from hundreds of Harry worshippers.

The vanishing act came as Rowling told how her latest book forced her to consider quitting as a writer.

She said: "It nearly caused me a nervous breakdown because for the first time ever I lost my plot."

More than 100 children, their parents and adult fans were out in force last night to welcome Rowling to Edinburgh - where her books are written - for the first time since the launch of Harry Potter and the Goblet of Fire.

The train pulled in to Platform 11, led by the Hogwarts Express with a blonde female waving from a window.

As the crowd of children surged forward, the author jumped from the last carriage and was whisked away. Parents had to carry their children away in tears.

Some families had travelled hundreds of miles to see the writer as she arrived for a book signing.

Eight-year-old Callum Mackay, of Dunure, Ayrshire, said: "I'm really surprised she just took off."

Later, outside the Assembly Halls, where the book signing was being held, 400 children who had won tickets for the event queued for more than an hour for a few seconds with the writer.

Earlier in the day, Rowling had hinted she would retire when the seventh and final Harry Potter book is published.

She said: "I will carry on writing but I don't know if I would publish again."

However, she said she had mixed feelings about the thought of leaving behind the characters which made her famous.

She said: "It is going to break my heart to say goodbye to them but there are aspects I won't miss."

Rowling, who has earned at least £15million from the schoolboy wizard series, said the latest book was the hardest to write. She said: "Book Four nearly caused me a nervous breakdown.

"I realised there was this big hole in the middle of the plot and I had to go back and unpick and redo."

Last night, aides insisted Rowling had carried out the ruse at Waverley Station because of concerns about the safety of children racing to see her.

At the signing later, Rowling looked tired and washed-out and admitted the publicity tour was taking its toll.

She said: "It's been really lots of fun but quite exhausting and complete madness."

Insisting she was "really happy", Rowling hid her mouth and face constantly behind her hands as photographers snapped pictures of her with the new book.

She could barely raise a smile for the cameras and at one point had to remind herself saying: "Oh yeah, I'm supposed to smile."

The Potter tour continues tomorrow when Rowling leaves Edinburgh, arriving in Perth Station between 12.15 to 2pm.