The Labour leader was visiting the market town of Ossett after Simon Lightwood’s victory in the vote when the trader initially offered him an apple. Sir Keir said thank you and went to take the fruit, but when he did the man grinned and passed him a lemon instead.
Deliveryman Paul Stoner, 60, said he asked him Sir Keir if he wanted an apple and when he said ‘yes’ he gave him a lemon because he thinks he is a bit of a joke.
Mr Stoner told Express.co.uk: “He said thank you. I think he thought it was an apple. It was just a joke. It was on the spur of the moment.
“It wasn’t a political act. I’m actually glad to see Labour get back in even though there’s a lot wrong with Labour. I’m a socialist at heart, a working man. Everyone is working class round here.”
The Conservatives lost two parliamentary seats on Friday in a crushing blow to the Prime Minister Boris Johnson’s party.
It prompted the resignation of its chairman Oliver Dowden and intensified doubts about the future of the PM.
The Liberal Democrats handed the Conservative Party its biggest by-election defeat in British history as the Tories lost a majority of 24,239 in Tiverton and Honiton.