Ken Clarke has asked David Cameron his final question as prime minister at PMQs.
He paid tribute to David Cameron's "wit and humour" and urged him to remain an "active participant".
Cameron joked that Clarke's first act as chancellor was to fire him as a special adviser.
He said Clarke had demonstrated "great wisdom, thoughtfulness and balance" during his time in the coalition government.
The appointment of Theresa May means there have been 13 UK prime ministers to serve Queen Elizabeth II.
From David Cameron's last Prime Minister's Questions, to Theresa May meeting The Queen, here is how the day unfolded in pictures.
Theresa May kept her first speech as prime minister short and to the point, as she vowed to lead a "better Britain" outside the EU.