London, Jan 2 : A new version of the Harry Potter encyclopaedia, which multi-millionaire author JK Rowling went to court to stop, is to go on sale in Britain later this month.

The 43-year-old author of Potter took Harry Potter fan and author Steve Vander Ark to court over the 400-page Lexicon which she said constituted "wholesale theft of 17 years of my hard work".

A US judge ruled in Rowling''s favour in a copyright-infringement lawsuit in September, permanently blocking the publication of the reference guide.

But now Steve Vander Ark is to publish a revised edition which he says meets specifications laid out in the ruling.

Vander Ark, a 50-year-old former school librarian who launched The Harry Potter Lexicon web site in 2000, spent five or six months working on the new version.

It also includes information revealed during the three-day court hearing in April, reports the Telegraph.

"We learned a lot at the trial about what was acceptable, what would follow the fair use guidelines," said Vander Ark, of Michigan.

"That was not clear before. There was no law on the books that made it clear what was acceptable and what wasn''t. So, coming out of the trial, I had a much better idea of what should go into the book," he added.

Publisher Roger Rapoport said the biggest difference between the two versions was that the new one contains "a lot more critical commentary, which means more analysis".

"It isn''t just saying what happens, it''s his interpretation of why it''s important," Rapoport said.

The Lexicon: An Unauthorised Guide to Harry Potter Fiction and Related Materials will go on sale in the UK on January 16. (ANI)