He was seen sipping a pint of Hawkstone stout at the Cotswolds pub on Friday as filming for the new season started on September 5.
The 59-year-old Lord lives near Chipping Norton and was MP for neighbouring Witney for 15 years.
The ex-Conservative Party leader appeared to be attending the Hawkstone Harvest Festival, which was being filmed for Clarkson’s Farm.
He told The Sun on Sunday that the motoring host turned farmer “has done an amazing job at highlighting some of the issues in the countryside.”
“He’s done more for farming than anyone else I can think of in recent years”, he continued.
He praised the “brilliant idea” of The Hawkstone Farmers Choir, adding that watching them has been “incredibly emotional”.
This comes as the Hawkstone Farmers Choir and Hawkstone Brewery are donating £100,000 to mental health and farming charities.
The choir sang their way to the final of the ITV show in May, where they picked up the jackpot of £250,000.
A £50,000 cheque was handed over at the pub on Friday – the same day Lord Cameron was there.
The brewery matched the £50,00 donation to Shout, which it has worked with since 2024, to establish a route for farmers to access its text-based mental health support.