Although I like to think I have better things to do with my time, I read all the accounts of the end of the marriage of Sir Mark Thatcher and his American wife, Diane. I confess that long before he allegedly got tangled up in financing coups, I thought Thatcher was creepy. A James Hewitt kind of guy. Not the kind of fellow you’d want your daughter to marry, even a daughter her daddy described as ‘just an ordinary millionairess’.

Of course, there’s a long tradition of Englishmen marrying ordinary American millionairesses. Think of Lord Curzon’s Mary Leiter. And Jenny Jerome, Churchill’s mother. But my favourite was Consuelo Vanderbilt, forced by her pushy mama into marriage to the Duke of Marlborough. Her father may have given the duke $2.5 million as a marriage settlement, but Consuelo was no ordinary millionairess. She found her husband’s family condescending; Englishwomen ill-educated and too dependent; and the Duke cold and boring. She left him in 1906, moved to London, worked for women’s suffrage and ran a home for prisoners’ wives.

My own English husband has never come right out and said he would have liked an ordinary millionairess, but early in our marriage, he sounded wistful when tracking my family tree. ‘Your family’s been in America 200 years and they don’t even own a chain of gas stations?’

That wistful tone stuck in my mind and I’ve worked hard to make up for the financial improvidence of my forebears. I’ve planted a vineyard, opened a country store and started a restaurant, but frankly, none of these enterprises produces the income of a string of BP stations. But last year I found the answer. Biodiesel.

I read in Farmers Weekly how to transform the used vegetable oil from our chips (hand-cut from our farm potatoes) into biodiesel that would run our tractors as well as the Peugeot and Land-Rover. The recipe sounds so simple: mix the used vegetable oil with methanol and lye. Then you get the details. You need the kit: £4,000 and you still have to pay duty-27.1p per litre, a tax requiring legal integrity quite beyond me. You also need a farm shed to house your distillery and a lavish supply of Jo Malone’s French Lime Blossom if you don’t want to arrive smelling of pommes frites.

But if my pursuit of biodiesel fortune has stalled, all is not lost. There is now bioethanol, better known as E85. Swedes are now using it to run their bio-powered Saabs. It costs 25% less than petrol, is made from wheat or sugar beet and can liberate us from the tyranny of Arab oil. It’s also kind to the environment: if ethanol replaced 5% of petrol in the UK, it would amount to taking one million cars off the road.

The Saab 9-5 Biopower engine can run on regular petrol if you can’t find an E85 pump (300 petrol stations now sell E85 in Sweden), and if you get really stuck, the engine will even run on a bottle of Claret, ethanol being the main active ingredient in vin rouge.

Meanwhile, I’ve taken our Wyken red wine off the shelves-the one I describe as ‘a feisty little wine best for cooking’- and I’m keeping it in storage until the car industry (and this Government) comes to its senses and paves the way for the Bioethanol Future. What with sugar beet, wheat and a seven-acre vineyard, I may convert this farm into a chain of gas stations after all. Just call me an ordinary millionairess-in-waiting.

This article first appeared in Country Life magazine on September 29, 2005.