When Richard Saville-Smith innocently bought his eleven year old son, Comrie, a domain name for his birthday, he never expected he would involved in a legal war with one of the world’s largest law firms and UN intellectual property regulators.

A special present for the young CS Lewis fan, the £70 purchase of the domain name Narnia.mobi has pitted the family against the author’s literary estate just before the UK premiere of the new Narnia film.

Mr Saville-Smith has been accused of buying the domain name in bad faith with the aim of making money from the Narnia name – a common internet practice known as cyber-squatting.

A 128-page dossier, compiled by the New York lawyers Baker & McKenzie, arrived at Saville-Smith’s home in Edinburgh this month, urging him to relinquish the domain or face a hearing at the Geneva HQ of the World Intellectual Property Organisation (WIPO), an arm of the UN which arbitrates on web law.

The domain has been frozen while the WIPO prepares to hear the case, which leaves Comrie with out his birthday present in the week of the UK release of Price Caspian, the second screen adaptation of The Chronicles of Narnia.

Saville-Smith denies any financial motive behind his purchase. He says he bought the domain legitimately in September 2006 after the expiry of a three-month “sunrise period” - a time when owners of a trademark can buy up all names relating to their name ahead of a general sale.

“We were amazed the domain name was still free and snapped it up for Comrie, who is a big fan of the Narnia books,” said Saville-Smith. “The people from CS Lewis must have realised they missed it, and now they want it back. They are trying to bully us into handing over our little boy’s present with lawyers and legal threats. But we … don’t take kindly to this kind of intimidation, we’re not backing down.”

A spokeswoman for Baker & McKenzie said the firm had to consult its client before commenting on the case.

Launched in the summer of 2006, the dotMobi phenomenon, which created sites for browsing on mobile phones, saw well-known firms scrambling to buy domain names linked to their trademarks. Domain name trading has seen large companies accused of “cyber squishing” - threatening small firms holding a domain name with legal action - and canny individuals snapping up popular site names for auction.

Saville-Smith stressed he would not back down. “It’s classic David versus Goliath stuff . We have no intention of making money out of it, it’s just for fun. To try to ruthlessly snatch away a gift intended for a young boy who loves his Narnia books is unbelievable.”

His wife, Gillian, said the Narnia address was one of several dotMobi names they had bought: “My husband bought me TheQueen.mobi and I bought him US President.mobi - so maybe George W Bush will be after us next.”

Asked what he thought of the whole thing, Comrie replied: “I think its all a bit weird.”