McDonald's has been stripped of its European Union trademark for the Big Mac hamburger in humiliating defeat after a “David and Goliath” legal battle with Supermac’s, an Irish fast food chain.

In a landmark judgment with immediate effect, the European Union Intellectual Property Office (EUIPO) said McDonald's has failed to prove “genuine use” of the Big Mac trademark as a burger or restaurant.

"Never mind David versus Goliath, this unique landmark decision is akin to the Connacht team winning against the All Blacks," said Pat McDonagh, the managing director and founder of Galway based Supermac’s. “This is the end of the McBully”.

“Just because McDonald's has deep pockets and we are relatively small in context doesn’t mean we weren’t going to fight our corner," he added.

Supermac’s has about 100 restaurant in Ireland and was founded in 1978. It has been locked in a legal battle with McDonald’s since 2015 when it planned to expand into the UK and rest of the EU.

The US company objected to Supermac’s applying for an EU-wide trademark, with lawyers sending a 41-page treatise arguing it was too similar to McDonald’s.

“Supermac” was Mr McDonagh’s nickname when he played Gaelic Football in his youth.