Getting out and going wild in a 4x4 can be fun, or so I am told. The trouble is that many owners of such vehicles have no land to rove over — which is why the Abingdon 4X4 Festival was so successful, earning £110,000 for charity over ten years. It provided the rough driving that many owners crave for their tough machines.

Until this year, that is. Then the organisers, the Rotary Club and the Phoenix Land Rover Club, could not agree a hiring fee with Ministry of Defence Estates for the use of the Dalton Barracks site at Abingdon Airfield, near Marcham — so they arranged to rent a field nearby from a local farmer instead.

The trouble with that arrangement was that only a hedge separated the chosen track from a nature reserve, adjoining a Site of Special Scientific Interest (SSSI) belonging to landowner and City financier John Duffield, who persuaded the organisers to call the whole thing off again.

The paradox here — reflecting in microcosm the current battle between consumerism and conservation as the Government examines relaxing planning laws in the countryside — is that the rural areas should need protecting from machines originally designed to cultivate and improve it.

Walking round the 130-acre reserve with Mr Duffield, pictured, we soon found ourselves talking about the very nature of capitalism itself vis-à-vis the business of preserving the natural world.

He said: “This story, about protecting this place from 4x4s, is actually a story without a villain. The organisers wanted a new site, found one, and then saw, after a little persuasion, that the chosen place was not after all suitable for their purpose.

“The vibrations, according to Natural England, would harm the natterjack toads. And then, perhaps more persuasively, there was the health and safety issue: this reserve is full of rabbit holes which competitors might have fallen into. And there was also the fact that a lot of dogs might have got loose in here.”

He did admit, however, that in persuading the organisers to call off the event he had agreed to donate £20,000 to charity, to make up for the money that the event might have raised. But he did not inform them which charity it would be.

He said: “I shall give the money to the Council to Protect Rural England this week.”

Multi-millionaire Mr Duffield, born in 1939, is a colourful City whizzkid of the old school, the son of a doctor who practised in nearby Marcham — where he still owns several houses.

He established Jupiter Fund Management in 1985, one of the largest fund managers in London, which he later sold to Commerzbank.

Then he founded the equally successful New Star Asset Management in 2001. That became Henderson New Star when he sold it to the Henderson Group in 2009. It was rebranded as Henderson Global Investors in 2010.

For many years he also managed the estates and money of his wife Vivien Clore, daughter of Selfridges owner Sir Charles Clore, from whom he was divorced in 1976.

Slightly sheepishly I asked him whether it were not odd that someone who did so much to fund development should be so keen to protect his land from its effects?

He said: “The trouble is that some things I do are necessary but not profitable. Others are not productive but are profitable.” (Shades there of author Ivy Compton Burnett who once said: “The trouble with things worthwhile is that they are worth so little else.”) He added: “In the City we are not productive. We shuffle bits of paper about. But capitalism couldn’t function without people doing what we do in the City. I am a Communist by inclination, but that has been proved not to work.”

But what he has achieved at his nature reserve, called either Glebe Field or Black Horse Field (whichever you prefer), at Gozzard’s Ford, near Abingdon, is certainly impressive.

A species of insect, a semi-aquatic leaf hopper (macrostelles cyane) which was thought to have become extinct has even been discovered there.

But the natterjack toad, now introduced to his reserve, seems to be his great love.

Jumping weirdly in our conversation between the activities of City people and those of toads, he told me: “Man is selfish — particularly towards other species.”

But why were the organisers of the Abingdon 4x4 event not able to use the Dalton Barracks as they had done in previous years?

Surely such a place is ideal? The main beneficiary of the event has been Thames Valley and Chiltern Air Ambulance Trust, with more than £50,000 in donations.

In a statement on the event website, the Rotary Club said the Defence Estates were expecting “substantially increased revenue” and wanted to impose more restrictions, which made the event no longer viable. The statement said: “The representative of Defence Estates seemed unwilling to take into account that this is a community event to raise money for local charities, which serve the residents of Dalton Barracks, Abingdon, and the wider community of Oxfordshire.”

It added: “Defence Estates would be expecting substantially increased revenue from the event in 2011, together with the imposition of a number of restrictions concerning the use of the site.”

The festival has raised money for charities such as Helen and Douglas House, Against Breast Cancer, the John Radcliffe Hospital, and Down’s Syndrome Oxford. This year it was hoped to stage a larger event.

Stevey McAleer, vice chairman of the Phoenix Land Rover Club, said: “They [Dalton Barracks] want more than we are charging at the moment, which leaves nothing for the charities.

“They put huge restrictions on the off-road course and on the number of vehicles. We will have less people coming and we will have to pay more money out.”

Ministry of Defence spokesman Becky Clark said the cost had risen as the application was for a bigger event. She said: “These charges were in keeping with the standard charges for such events, which are regularised countrywide by the MoD.”

Here’s hoping that next year everyone may live in harmony including off-roaders, conservationists, and the Ministry of Defence.