A father-and-son who turned down £50,000 of investment for a garden gadget on BBC2’s Dragons’ Denhave told how they have no regrets about walking away from the deal.

The Wheelbarrow Booster was pitched on BBC2’s Dragons’ Den

Yorkshireman Mike Smith and son Joe pitched their Wheelbarrow Booster (see below) to the show’s five multi-millionaire investors, offering 10 per cent equity in their company in exchange for a cash injection.

But when dragons Duncan Bannatyne and Hilary Devey teamed up to offer £50,000, they demanded 50 per cent of Mike and Joe’s company, GreanBase.

It led Mike to remark that he would not give away more than 11.5 per cent of his company, prompting one of the most heated exchanges seen on BBC2’s top series. They walked away empty-handed. Joe said: “The dragons wanted 50 per cent so we said no, s*d you!”

He went on: “My father had never watched Dragons’ Den before – he thought Lord Sugar was on it – and he hasn’t watched it since.

“He didn’t even see the programme we were on, as he was watching Downton Abbey.”

Wheelbarrow Booster inventor Mike argued with the Dragons

Asked about his father’s on-screen row with dragon Deborah Meaden, Joe said: “My father answers only to himself. I think he became a bit sick of them [the dragons].

“We may have negotiated to 25-30 per cent equity but my father can speak before he thinks. I found it quite amusing! It’s a shame we forgot to mention that Alan Titchmarsh had endorsed the product, which has also been on Simon Mayo’s radio show.”

However, the inventors remain upbeat after Homebase ordered 5,000 Wheelbarrow Boosters for 2013, while Tesco Direct has also listed the £12.99 product.

At a recent trade show in Birmingham, Mike and Joe took 2,000 orders.

Joe, who said he had been approached by private investors since the programmed aired, summed up: “We went in with nothing to lose. After all, the Dragons are only five other people.”

What is a Wheelbarrow Booster?

The booster can increase the capacity of a wheelbarrow by up to 300 per cent

It is aimed at cutting the number of trips between garden and compost heap

The booster can be folded away when not in use

It was invented by Mike Smith almost 20 years ago