Children's suitcase brand Trunki has lost its legal battle with Hong Kong rival Kiddee, after the UK's Supreme Court ruled that design rights had not been infringed.

UK-based company Magmatic, which designed the ride-on Trunki suitcase, claimed that Hong Kong company PMS had infringed its registered design rights with its lookalike version of an animal-themed ride-on suitcase named Kiddee.

But five Supreme Court justices unanimously disagreed, and ruled in favour of PMS on Wednesday – stating that while it had "sympathy for Magmatic", the "Design Right is intended to protect designs not ideas".

Magmatic registered its designs for Trunki in 2003, while PMS came up with Kiddee in 2013 as a model for the discount market.

According to the Guardian, PMS managing director Paul Beverley has openly admitted that he came up with the idea for Kiddee Cases after seeing Trunki luggage.

He described the court's decision as a "victory for fair competition", stating that it "ensures that the Kiddee Case can continue to be sold to price-conscious UK families".

Magmatic won a High Court judgment against PMS in July 2013, but this was overturned in March 2014 after the court of appeal ruled that the Kiddee case looked sufficiently different to the Trunki one.

Trunki has since been on a two-year campaign to uphold the 2013 high court judgment against PMS.

The company's founder Rob Law gained the support of some of the country's leading design figures, including Terence Conran, Kevin McCloud, and Brompton bikes CEO Will Butler-Adams.

He argued that the court ruling undermines the rights of hundreds of thousands of British design-focussed businesses, leaving them open to design infringement.

"We are devastated and bewildered by this judgment, not just for ourselves but for the huge wave of uncertainty it brings to designers across Britain," said Law. "We created an original product in Trunki and protected it by computer generated registered design – a process used to protect a third of designs across Europe."

"In my honest opinion, the Trunki was willfully ripped off," he added. "We stood up to this behaviour, held it to account and took our case all the way to the highest court in the land – only for the judges to rule that we are not protected against the copy. They're effectively sending knights into battle without armour."

Law believes that the decision puts British designers at a disadvantage compared to their European counterparts, stating that courts on the continent offer a "far more robust approach to infringement".

"The law is meant to be about certainty," he said. "But this decision will create chaos and confusion among Britain's design community, who have relied on a pan-European right which has been in place since 2002."

In 2014, the UK government was attacked by design brands including Vitra, Artek and Flos for delaying the implementation of a law that would ban the sale of copies of their furniture and lighting products.

The brands have since formed a coalition to lobby the government after learning that the law – passed in 2013 – will not be brought into effect until 2020.

"The UK has never had the same level of intellectual property protection as the rest of Europe," said Tony Ash, managing director of Vitra in the UK, USA, India, Middle East and Far East. "There it's 70 years plus the lifetime of the creator but here it's 25 years from creation. So we've always been at a disadvantage. We lose business and the designers lose royalties."