Theresa May's use of "simples" last week was apparently the result of a bet by her senior advisers.
The quote is best known as the catchphrase of fictional meerkat Aleksandr Orlov, who appears in adverts for price comparison website comparethemarket.com.
It was revealed the line was inserted into the Prime Minister’s speech as part of a bet between Mrs May’s closest aid Seema Kennedy and Tory MP Simon Hoare to win tea at the Ritz hotel.
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Speaking to talkRADIO’s Mike Graham, Mrs May's former aide Katie Perrior said: “We all play practical jokes in politics because it can be very, very dull, very miserable, and soul destroying, so sometimes you do need a little bit of gallows humour to get you through the week.
“But that is a very senior level to start messing about. Theresa May doesn’t watch adverts so there’s no way she would have known about that advert.
“I didn’t really like it and I don’t think it sat well with her. She would be pretty furious I should imagine that she’s been hoodwinked in that way.”
Ms Perrior also revealed that Penny Mordaunt was once reprimanded by David Cameron for taking on a bet that she could say a certain rude word in the House of Commons, which she did so by joining a debate on farmyard animals.
"He thought it was very funny, but did tell her never to do something like that again," she added.
Ms Perrior said former colleagues were complaining of a "toxic" atmosphere at Number 10.
Ms Perrior said she would occasionally play games at Number 10, such as organising an easter-egg hunt for journalists, but added insiders had told her those days were “long gone”.
She said: “They are just surviving day-by-day, hour-by-hour, week-by-week. They’re just in survival mode.
“I was recently told by several people that they’ve gone to work for the royals because they believed in public service but couldn’t face working at Number 10 anymore.
“The atmosphere has become really toxic and many people are just desperate to get out.”