INVENTOR David Gattie entered the Dragons Den to pitch his Anti-Draught Air Vent for stoves.

David and his son Max demonstrated the invention on the BBC TV series in a bid to attract a £40,000 investment.

Despite failing to win over the dragons David remained optimistic about the future for his invention.

David, from Knutsford, said: “I believe the market is huge – obviously it is not huge enough for them [the dragons]. It was a good experience.”

Max said: “It’s a very good product, and I think the product will live on.”

David, who retired a few years ago, installed stoves for eight years, and put in more than 1,100.

He said: “Retirement did not suit me at all – work keeps your brain alive.

“I have invented a new type of air vent which virtually eliminates the draught which often results from having a stove installed in your house.

“I invented the DR21 Anti-draft Air Vent – which you can see working at Our product helps address the problems of air pollution, which has had considerable media coverage recently.

“Stoves often lack a sufficient air supply because the vent causes a draught and is blocked up by the homeowner. The DR21 vent prevents the draught and solves this problem.

“The DR21 air vent is one of the most exciting developments in solid fuel installation in years.”