The company he co-founded, Ora Media, did not state a cause of death but media reports said King had been battling COVID-19 for weeks and had suffered several health problems in recent years.
Channel 4 said their one-hour live debate was for party leaders only but Prime Minister Boris Johnson declined to take part.
The latest televised debate between the two Conservative contenders vying to be Britain's next prime minister was abruptly halted on Tuesday evening after the moderator fainted on stage.
For Le Pen, who is behind Macron in opinion polls ahead of Sunday's vote, it is all about showing that she has the stature to be president and convincing more voters that they should not fear seeing the far-right in power.
Spain’s acting prime minister hardened his stance on Catalonia in a live TV debate with his rivals, ahead of a repeat general election which polls suggest will lead to another inconclusive outcome.