Trunki designer Rob Law
Trunki designer Rob Law, whose company claimed its design (R) had been flagrantly infringed by Kiddee Case (L)Trunki

Judgment was reserved in a case involving a company founded by one of the most successful rejects on BBC TV show Dragons' Den, which accused another brand of a "flagrant design infringement" at the Supreme Court.

Trunki, the makers of the wheelie suitcases for children, alleged another company was infringing its European Community Registered Design on the specific shape of the suitcases.

Magmatic, the business behind ride-on suitcase Trunki, had already won a High Court judgment against PMS International in July 2013. It successfully argued its design was infringed by PMS's Kiddee Case.

But that decision was later reversed by the Court of Appeal and sent to the Supreme Court, which rarely grants permission to appeal. Only 89 appeals were heard in 2014 despite 229 applications being received.

Entrepreneur Rob Law came up with his idea for the Trunki in 1997 but was turned down when he appeared on Dragons' Den in 2006 seeking funding for the venture. While the Dragons initially took a liking to the product, after Theo Paphitis managed to break one of the straps, they began to question its quality.

Peter Jones then attacked his million pound valuation, telling him: "This type of product is not patentable." He added that he was really concerned "because in seven days I could do a better job than that.... I could have this in production by the end of next month. Your company is currently worthless. I'm out".

Nine years on, though, the business continues to be a success story, with the latest published revenue sitting at a comfortable £7.7m in 2014.

Duncan Bannatyne and Jones have both since admitted that they regret not investing in Trunki in the past. The judgment, reserved on 3 November, is expected in 2016.