Zac Goldsmith assumed that, with a majority of 23-thousand, he could easily retain his seat. It turned out to be a far bigger miscalculation than his faintly disastrous campaign for London Mayor earlier this year.
The warning signs were there. Almost three-quarters of his former constituents voted Remain in the EU referendum, while he campaigned for leave. And the Liberal Democrats, who held the seat until 2010, managed a swing of 20% in David Cameron’s old constituency just a few weeks ago.
Mr Goldsmith’s team, almost all on loan from the Conservative party he was officially independent of, talked up the honourable actions of their candidate, keeping a promise to resign his seat if the Tories approved Heathrow expansion.
But it was clear that, apart from this one issue, he would have sat and voted as a Conservative in all but name.
The Lib Dems, with nothing to lose, threw everything at Sarah Olney's campaign in Richmond, sensing the huge publicity value in pulling off an upset. What better way to proclaim your comeback is underway?
It’s a howl of protest by dismayed Remain voters, still furious at the outcome of June’s referendum.
While that’s easily dismissed as the rantings of “Remoaners”, it’s worth remembering there are 16-million of them, including more than one-third of Tory voters. Labour’s vote collapsed in Richmond, to deposit-losing levels. And with both the Tories and Labour lining up behind Brexit, there are plenty of disconnected voters potentially looking for a new home.
Let’s keep a sense of perspective. Nationally, the Liberal Democrats remain on around 8% in opinion polls, with the Conservatives north of 40%. Had this been a general election the Tories would have a sharply increased majority.
But Richmond Park has further narrowed Theresa May's already narrow majority. The Lib Dems will take great heart from Sarah Olney’s victory, and see the potential to double their numbers in Parliament in 2020.
And while the Brexit vote may be history, the battle is clearly far from over.