Jacqueline Wilson walked out of a Bournemouth bookshop early yesterday having unexpectedly chalked up what could be a record for the longest book signing in British history.

The bestselling children's writer walked into Waterstone's Bournemouth Castlepoint store at 3.30pm on Monday anticipating that her visit would last only a few hours. But she ended up signing until midnight, for a queue of more than 3,000 people, mostly children.

By contrast, 600 people turned up for a Waterstone's book signing with the former England rugby captain Martin Johnson, and 500 for the motor racing commentator Murray Walker. The Harry Potter author JK Rowling only attends signings for specially invited groups of fans.

David Lund, the manager of the Bournemouth store, said: "Jacqueline agreed to stay and ensure that everyone was in the queue had a chance to meet her. All her fans were very patient."

Waterstone's yesterday nominated Wilson for an entry in Guinness World Records, but was refused because the record had not been monitored.

The writer, who last month deposed Catherine Cookson as the most borrowed author in libraries, told the Guardian: "I hope teachers in Bournemouth will forgive me for being the cause of many very tired pupils today."