JK Rowling has denounced Katie Hopkins and Fox News after the former Apprentice contestant said Britons were “cowed” following the terrorist attack on Westminster.

After four people, including the assailant, were killed outside Parliament on Wednesday, Ms Hopkins told the US network Britain was “tiptoeing around cultures that join us”.

“People are cowed by one particular religion, which is promoted by the Muslim mayor, Sadiq Khan, son of the bus driver,” she said.

“People are cowed, people are afraid, and people are not united,” she continued. “Great Britain is more disunited, it is absolutely divided, more than at any time in its past, and we are in fact a nation of ghettos.

“I think liberals here actually think multiculturalism actually means we all die together, and that’s not a view I support."

Taking to Twitter, the Harry Potter author compared Ms Hopkins’ comments to the defeatist attitude of a former US ambassador’s view that Britain would lose the Second World War.

Sharing a letter sent to US President Franklin D Roosevelt from 1940, Ms Rowling wrote: “As @FoxNews and @KTHopkins tell the world that terror is cowing London, I remember pro-appeasement US Ambassador, Joseph Kennedy."

The letter reads: "The night raids are continuing to do, I think, substantial damage, and the day raids of the last three days have dealt most serious blows to Bristol, Southampton, and Liverpool. Production is definitely falling, regardless of what reports you may be getting, and with transportation smashed up the way it is, the present production output will continue to fall.

Katie Hopkins gave an interview to Fox News in which she described Britain as 'divided' (PA)

"My own feeling is that… [the British] are in a bad way. Bombers have got through in the daytime on the last three days, and on four occasions today substantial numbers of German planes have flown over London and have done some daylight bombing.