Lib Dem Sarah Green is the country’s newest MP after winning the seat, which had been a Conservative stronghold since its creation in 1974.
In a stunning result, Ms Green took 56.7% of the vote to secure a majority of 8,028 over the second-placed Tories.
Here’s what you need to know about the politician who pulled off the stunning upset.
What did Sarah Green say in her speech?
In her acceptance speech Ms Green said: “Tonight the voice of Chesham and Amersham is unmistakable. Together we have said, ‘Enough is enough, we will be heard and this Government will listen’.
“This campaign has shown that no matter where you live, or how supposedly safe a constituency may appear to be, if you want a Liberal Democrat member of Parliament, you can have a Liberal Democrat Member of Parliament.”
She added: “We will continue the work of holding this Government to account for letting Covid rip through the care homes. We will speak up for the three million people excluded from financial support throughout the pandemic and we will challenge Boris Johnson to be far more ambitious in tackling climate change, supporting our frontline workers and backing our small businesses.”
Who is Sarah Green?
Sarah Green is a marketing executive who set up her own business in 2014.
According to her offical website the company “provides training and helps companies and individuals make their voices heard more effectively.”
The website adds that she is an “independently-minded campaigner and entrepreneur determined to get things done for our local community”.
Green joined the party in 2005 due to her opposition to the Iraq War.
She has run for MP on two occasions, once in 2005 for the Ynys Môn and once for Arfon in 2010.
The new MP lists support for small and medium sized businesses protection of the environment and green spaces and more support for local public services as her priorities.
What has loser Peter Fleet said?
Defeated candidate Peter Fleet acknowledged the Conservatives had to rebuild “trust and understanding” with voters.
Mr Fleet said: “Clearly this was a very disappointing result, not the result that I was expecting, nor my team.”
Fleet appeared to attribute the victory to the Liberal Democrats’ work ethic.
He said: “The Liberal Democrats didn't just throw the kitchen sink at this constituency, it was the microwave, the table, the oven, the dishwasher, the dog, the cat and anything else that was lying around as well.”