Charles Moore, former editor of The Daily Telegraph and The Spectator, made the comparison in an interview with The Times that coincides with the third volume of his Thatcher biography being published.
He said the current Prime Minister was, in some ways, the opposite of Margaret Thatcher who “would never wing it like him” but there were also similarities, including the way they both ended up being PM.
“It was a sense there had to be someone different,” he said. “In that sense it was like Boris — they only finally chose him when they ran out of everyone else.”
Describing both as “good explainers”, he said: “Boris doesn’t expound policy like Mrs Thatcher sometimes did, but they both understand the big message. Britain being a great place, freedom being so important.”
Mr Moore described both as “loners” who were also “gregarious”: “Mrs Thatcher despite relying on her own resources didn’t like being alone. I suspect Boris is like that.”
“It was probably beneficial that Boris didn’t become prime minister straight after the referendum and Michael Gove did him in because now he’s absolutely serious about what he has to do. It’s not a game anymore, the iron has entered his soul.”
Asked about Mr Johnson’s “lying”, Mr Moore said: “I don’t like using the word lying for politicians. I don’t think he is particularly truthful, but Bill Clinton and Tony Blair were similar, they would use words cleverly and get round things. I would say shifty. He is certainly a much less scrupulously honest person than Mrs Thatcher but he’s not out of the ordinary for politicians.”
On the subject of the Prime Minister’s personal life, he said: “I would be surprised if he had led a monk’s life, he’s not like that, but I don’t think it’s a fit subject on which his public performance should be judged.”