In an interview with GQ magazine to be published later this week, the prime minister claimed he had known "for some time" that the Sun was planning to switch allegiances but said he still respected the paper's proprietor, Rupert Murdoch.
The News International paper's decision to endorse David Cameron hours after Brown's speech to the Labour party conference in late September overshadowed the prime minister's address and was a hugely symbolic moment. The Sun had backed Labour for more than a decade.
"I have a lot of admiration for Rupert Murdoch personally," Brown told GQ's interviewer, Piers Morgan. "His family come from not far from mine in Scotland, and his attitudes to hard work and getting on with things you can only admire. But the Sun has tried to