The experts on Dragons’ Den told Rob Law his idea for a children’s suitcase was worthless – but now it is worth more than £1 million a year to him.

He first came up with the idea for Trunki, the children’s suitcase on wheels that doubles up as a ride-on toy, in 1997. And despite the reaction from the Dragons he put thousands of his own money into developing it.

Today the brightly coloured suitcases sell in 40 countries and customers include John Lewis and Debenhams.

Rob, of Clifton, has 10 people working for him on marketing, graphics, design and sales.

He has come a long way since the BBC’s dragons sent him away without a penny of investment. But he says the experience did a lot of good as well. His company now has a turnover of more than £1m a year.

He said: “I can now thank the dragons, hand on heart, because by just being on the show, even though we didn’t get the investment, we got a lot of exposure and it was really good for our profile.”

Mr Law, who did get help from the Prince’s Trust, said he was pleased to reach the three-year mark, particularly in the current economic climate with many new businesses struggling.

He believes the secret of his success was to start small and grow gradually.

He said: “One of the reasons why we have been able to remain successful is that we export Trunki to 40 countries and companies that are exporting are doing better at the moment.

"There are a couple of factors which have helped us over the past three years. Firstly, the business grew slowly. We started off supplying Trunki to a few independent shops at first and they really had a passion for the product.

“Small independents are quite often run by parents and they understood immediately what Trunki was and how children would want to use it.

“So they were willing to take the risk with the new product and now we supply to about 300 independent retailers. When the big stores saw what a success it became they wanted to stock it as well.

“The other factor is that children make friends with their Trunki, which is designed for three to six-year- olds, and form a bond with it.

“There are certain characteristics on the cases but children can also use their imagination and form a relationship with it the way they want.”

Mr Law, who is currently appearing in an Orange mobile phone advertising campaign, said people should not be put off developing a business idea during a recession and that he was only able to develop Trunki because he had the time on his hands during the last downturn.

He said: “The business was started in 2003, which was the tail-end of a global slow-down. I had been working abroad on my design career and when I came back to the UK I couldn’t find any work. So I took advantage of the time I had on my hands to properly investigate the idea of the Trunki.

“During times like these, if you have an idea it could be a good time to develop it because it takes a lot of time at the start to fully explore if an idea will work.”

Mr Law said he hoped to continue to grow the business and make it easier for parents to take their children abroad.

He said: “It is a wonderful experience for children to be able to travel abroad and discover new cultures, it is incredibly enriching.

“I want to help make that easier by coming up with travel products that make the process of going abroad or on holiday a little easier.”

On Monday Rob is holding a third birthday party for Trunki when he will release 400 balloons in Millennium Square.