Theresa May has mocked Jeremy Corbyn’s “incredible” leadership while apparently attempting to make a joke during Prime Minister’s Questions.

The Prime Minister was responding to a question on changes to disability benefits but used her answer to taunt Labour over its defeat to the Conservatives in last week’s by-election in Copeland, Cumbria.

The exchange came during a muted session of Prime Minister’s Questions in which Mr Corbyn pressed Ms May on the issue of changes to Personal Independent Payment (PIP) disability benefits. 

The Leader of the Opposition demanded the Government rethink the “nasty” changes, saying they were penalising vulnerable people with mental illnesses. 

Ms May responded: “The way that we are dealing with disability benefits is to ensure that payments are going to those who are most vulnerable.

“He talks about funding and about borrowing…I understand the Labour Shadow Health Secretary [Jon Ashworth] today, when asked how Labour would pay for the increase if it was put in place, said ‘Er, we’ve not outlined that yet’", she continued.

“That just sums up the Labour Party and the Labour Party leadership.

"After the result in Copeland last week, the Honourable Member for Lancaster and Fleetwood [Cat Smith] summed up the by-election result by saying it was an incredible result for the Labour Party."

To muted laughter from the Tory benches, Ms May added: “ “You know, I think that word actually describes the Right Honourable Gentleman’s [Jeremy Corbyn's] leadership. In-cred-ible.”