South Thanet Conservative MP Craig Mackinlay breached rules
An MP broke parliamentary rules after failing to register business interests in a dormant airline company, in which he was the sole shareholder.
South Thanet Conservative MP Craig Mackinlay had the allegation against him was upheld by the parliamentary standards commissioner.
Mr Mackinlay apologised, telling MPs his plans never got off the ground.
The standards commissioner said MPs must register an interest if they hold more than 15% of a company's shares, or their shares are worth more than £70,000.
Ms Stone found on two occasions Mr Mackinlay had failed to declare his interest when it would have been relevant to parliamentary proceedings.
She said he would have been expected to declare his interest in Mama Airlines when speaking in Parliament in support of the reopening of Manston Airport, which closed in 2014.
Mr Mackinlay said Mama Airlines, which was set up in 2001 with the intention of flying out of Manston to Malaga in Spain, was "unlikely" to ever trade.
He told MPs in the House of Commons: "The company has never traded, has never had a bank account, and has 2p of share capital which I own."
Mr Mackinlay said he had never hidden his interest in Mama Airlines.
"Following 9/11 it never came to anything and plans ceased," he told MPs.
"It remains a dormant company... Despite the name, this company is no more an airline company than it is a furniture company or a sweet shop."