Commons Speaker John Bercow has suggested that the EU referendum result could have been different if 16-year-olds were allowed to take part, and refusing to lower the voting age may be a decision some MPs now regret.
David Cameron's government repeatedly opposed attempts in Parliament to extend the franchise to 16 and 17-year-olds, but Mr Bercow suggested that the support among younger Britons for the European Union could have swayed the outcome.
Bercow, whose role demands he is strictly impartial, said the outcome of the referendum - which saw the UK back Brexit by 52% to 48% - came as a surprise.
At an event in Speaker's House within the Palace of Westminster he said: "I must keep out of these arguments ... I must admit I was surprised. I did think that the Remain campaign would win, like most people.
"The only obvious point - which gets us absolutely nowhere, I know - is that looking back, and Parliament passed the legislation perfectly properly, the EU Referendum Bill, which became the EU Referendum Act.
"Looking back, I just sometimes wonder whether people on the Government side who were supporting the Government's official position rue the day that they voted down the amendment or new clause that would have given the vote to 16 and 17-year-olds."
He said it was a "matter of fact" that "whereas 16 and 17-year-olds voting in the Scottish referendum were unhelpful from the British government's point of view - legitimate and exciting and contributing to a hugely interesting campaign, but unhelpful from the status quo point of view - in this referendum of course it would have been almost certainly the other way around".
Bercow has championed the involvement of young people in politics, allowing the House of Commons chamber to be used by the UK Youth Parliament.
Attempts in the Commons to lower the voting age were defeated, but peers passed an amendment which would have extended the franchise.
The proposed change in the law was overturned when the legislation returned to the Commons and only those aged 18 and over were allowed to vote in the Brexit referendum.