A digger and workmen were seen at the site in Harvil Road on Monday (October 2) as they carried out a "site clearance" on behalf of HS2 Ltd.
The protester - hoping to halt the work - is "under the digger".
Pictures from the scene show the workmen, in protective orange clothing, standing around while the digger remains still.
We'll be bringing you the latest updates, pictures and videos from the protests.
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We have the latest updates on today’s live blog, please follow the link below:
That's all from us
That’s all for our live updates on the anti-HS2 protest in Harefield.
For those who missed it, a campaigner is protesting in a bid to halt trees from being chopped down on Harvil Road.
She remained under a digger for hours, hoping to halt the progress of the high-speed rail link’s workmen.
At present, the protester remains under the digger, and her family are unsure how long the protest will continue for.
We will update you with the latest in the morning, but until then you can catch up on today’s events here.
Stocking up on supplies
Campaigners are preparing for an evening at the site, getting blankets and food as the protest continues.
We’ll bring you more updates as we get them.
In the meantime, take a look at what’s been going on in Harefield so far.
Campaigners call for support
Campaigners at the scene are looking for support from passersby in Harefield.
A spokesman for HS2 spoke to getwestlondon and said the company owns the land and has the relevant permission to undertake work.
He said the Harvil Road site forms part of the early works programme preparing the route for the construction of the railway.
“We are currently investigating an incident at our site on Harvil Road.
“We will update once more information is available.
“The safety of the local community and our people remains our main priority.”
"Stop killing nature"
Campaigners in Harefield have written “stop killing nature” on Harvil Road in an attempt to halt the progress of HS2.
A number of workmen can be seen in the background of the site, where a protester remains under a digger.
Live in Harefield
Our reporter Lois Swinnerton is currently live on Facebook in Harefield.
A protester has been sat under a digger in Harvil Lane for several hours now.
Head over to our Facebook page to go live to the anti-HS2 protest.
What is the Green Party stance on HS2?
Protester Sarah Green is a member of The Green Party, who branded the Transport Secretary’s plans to press ahead with HS2 a ‘colossal waste of precious resources’.
Responding to Chris Grayling’s speech at the Conservative Conference, Caroline Russell, Green transport spokesperson and London Assembly Member, said:
“It is unbelievable that the Transport Secretary is pressing ahead with plans for HS2 in the face of all the evidence that the project is a colossal waste of precious resources.
“The line will shave minutes off journeys to London while channelling funding away from where it’s really needed - providing people with improved local rail connections between our towns and cities across the country.”
Police arrive on the scene of the protest
Police officers are now at the field where the protester is sitting under a digger, in Harvil Lane.
Footage live from the scene of the protest
Our reporter, Lois, has sent us this video live from the scene.
Campaigners are urging Stop HS2 supporters to join in
Sally Cakebread, of Denham Against HS2, who is also at the scene, said:
“Any Stop HS2 supporters please come down.
“You can park in the Dogs Trust car park 200 metres away.
“We need support!”
Protester has now been sat under the digger for three hours
Protester Sarah explained that an Osprey, a species rarely sighted in London, was found at a lake near to the demolition.
She said: “I’ll stay out here as long as I can.”
The Green Party member added that she doesn’t mind if it starts raining, as she has shelter “under the digger!”
Green Party protester tells of her concerns over tree felling
Our reporter, Lois Swinnerton, is at the scene in Harefield and has spoken to the protester - Sarah Green, of Hillingdon Green Party.
Ms Green drives a passenger boat in the nature reserve in Denham country park. She said:
“As you can see there are a lot of trees that have been chopped down and bulldozed.”
So why is there a protester blocking the digger?
Mark Keir, from Hillingdon Green Party, explains:
Pictures from the scene in Harvil Road
Tree-felling work has halted as a protester is sat under the digger.