The Metropolitan Police said on Tuesday evening conditions have been put in place to prevent people bringing vehicles including tractors and agricultural vehicles to the protest in Whitehall.

The force has been contacted for comment.

But more than a dozen tractors could be seen parked outside Parliament on Wednesday morning, with rush-hour traffic brought to a standstill and farmers repeatedly sounding the tractor horns while police stood watching.

David Gunn, an arable farmer and agricultural contractor from near Sevenoaks in Kent, said he was protesting on Budget day for a number of reasons, including the Government move to put inheritance tax on larger farm businesses.

He said: “Inheritance tax is one reason, it’s going to cripple the farmers, the small family farmers.

“There’s all the other taxes they’ve been putting on us, and the prices we get for our produce and what it costs in the shop, we don’t make any money.

“Then there’s food security, farmers are going out of business.”

He said his message to Government was: “Sort the pledge out.”

“You said in the manifesto you would look after the farmers, which you totally haven’t, you’ve ruined the countryside,” he said.

Wednesday’s protest comes as Ms Reeves is facing pressure from farmers to axe plans to introduce inheritance tax on farming land and businesses.

The Chancellor’s plans to introduce a 20% rate on agricultural land and businesses worth more than £1 million have become a political flashpoint for a sector struggling with rising costs, tough market conditions and worsening climate impacts.

Last December, thousands of protesters gathered along Whitehall and angry farmers drove their tractors outside Parliament, demonstrating against the decision which farmers said put their businesses, futures and food security at risk.