Keen Harry Potter fans Laura Tisdall, 13, and Polly Tisdall, 11, were among hundreds of children who turned out to meet JK Rowling in Didcot, Oxfordshire, on Saturday. This is their account of what happened:

The moment the Hogwarts Express steam train finally puffed into Didcot Railway Centre on Saturday with JK Rowling on board was just totally magic. We'd been waiting for ages and ages with hundreds of other people, clutching our copies of the new Harry Potter book and our precious golden tickets.

We had sat a mock Hogwarts School Exam at Ottakar's bookshop in Chippenham, Wiltshire, and won a golden ticket each, which meant we could meet our favourite author and have our books signed by her.

A queue of excited kids and their parents stretched down the track waiting for the sound of a train whistle. To keep us entertained, and perfect for a signing of Harry Potter and the Goblet of Fire, a man was juggling fire sticks.

Then at last the maroon Hogwarts Express chugged in with a plume of steam, drawing beautiful antique carriages. There she was: JK Rowling herself!

She climbed aboard a stationary carriage, ready to meet us. Three hundred pairs of eyes watched her. Finally we moved forward through the iron archway with Platform 9 over it, just like in the books, and on to the train, moving a few steps closer. When it was our turn, we almost ran down the corridor and entered her compartment.

JK Rowling said she liked our T-shirts; one had a dragon on it, the other a lightning bolt, like the one on Harry's forehead. She was really friendly, not rushed. She was wearing a flowery skirt. She gave the answer to one of our questions about the second book, which we'd been dying to know. Then she signed our new books.

It wasn't all over. A family we had talked to in the queue had come without golden tickets. Luckily they got in, after waiting for 3 hours. Their mum said: "It was well worth it."

We thought so, too.