They came for 'Percy Thrower' last night. I was on my way to deliver some Pink Brandywine tomato seeds when I saw the first police car. I turned the corner and saw a fleet of them parked outside her house, complete with sniffer dogs and a space-suited forensic team heading for her potting shed.

I averted my eyes and walked past on the opposite side of the road, feeling the envelope of illegal seeds in my pack broadcast my guilt. As I left her road, the sterilization van arrived, its flame throwers ready to destroy 'Percy's' irreplaceable collection of plants.

I got away. The others weren't so lucky. As I waited for the bus I checked our secure server and realized they were rolling up the whole network. 'Monty' had been the first, but in catapulting a package of herb seeds into Buckingham Palace gardens he'd gone too far. His arrest had been the trigger for raids across the country. 'Bob' had sent out a warning as they smashed down his door, but they'd been ready for us all. If I hadn't been on a delivery run they'd've caught me as well.

I couldn't go home. Most of the people I trusted had been picked up. I stayed on the bus as it passed my stop and headed into central London. The clean-up crews were obvious, torching collections of wild flowers in the roadside beds that I'd seeded from bus windows while commuting.

All the hard work, all the beautiful, irreplaceable diversity, stamped out by commercial greed. If I'd've had the machinery with me I'd've leapt off the bus and seeded the palace gardens myself.

'Percy' had started the whole thing with a few prophetic words: “Biology is the biggest peer-to-peer copying system on the planet. Now they've eliminated file sharing they'll come for the seed sharers.”

She'd been a university botanist for years but left when it became clear that all the grants were controlled by big agribusiness. We knew we were in trouble when Kew was sold off and Henry Doubleday broken up. Their vast seed collections became the intellectual property of a few huge corporations. Unlicensed seeds were already illegal to sell, but once companies owned the rare strains, they stopped collectors sharing them for free. They wanted to control it all.

At first we tried to stop them. There were protests, lobbies and mass marches. Gardener's Question Time became such a political hot potato it was cancelled by the BBC. And then came the Chelsea Flower-Show Riots.

When I got off the bus I saw the police at the station. But it was just the usual patrols, not yet a manhunt. Maybe word of my escape had yet to reach them. I headed for Left Luggage.

We were called economic terrorists, threatening profits from high-cost, high-yield, terminator-gene strains that would feed the world and soak up excess CO2. But we just wanted tasty vegetables from our own gardens, unusual flowers smelling as good as they looked, and the opportunity to eat the occasional purple carrot. Serious action only came when self-propagating super-plants were found growing by a road in Norfolk.

Credit: JACEY

“Businessmen don't understand that biology is a lot messier than digital copying,” 'Percy' had said as we talked in her potting shed. “There's a dozen perfectly natural ways the terminator gene might have failed. One cosmic ray taking out the right base pair would be enough!” But scientific sense was never going to stand up to irate politicians shouting “Something must be done!” Fines became prison sentences, the Seed Squads were established and we were forced underground. Home gardens were no longer safe, so we became guerrilla gardeners — a secret society sharing seeds and planting contraband crops in public spaces. We tended them at night or just scattered seeds far and wide to let nature take its course. That's when the network started and we adopted our noms de vert.

We were too successful. Nature was indeed the great copier. Our wilder strains could fend for themselves and started to spread. The gloves finally came off when the director of Smaxo's agricultural division found a clump of illegal Afghan Purple carrots growing at the bottom of his garden and carpeted the Prime Minister. Of course, 'Monty' and his catapult didn't help.

Now the only guerrilla gardener left is me.

I collected my escape stash from Left Luggage along with Monty's seed catapult. The wig, hat and glasses helped me slip past the tighter police patrols and onto the sleeper to Fort William. Locked in my cabin I shaved my distinctive beard and used clippers so that I'd match the fake ID in my stash. The train would go through a lot of isolated country. The clean up crews couldn't cover all that ground in one season, so some of my seeds were going out of the window.

As for the rest ...

There are islands off the Scottish coast contaminated by bioweapons testing from the Second World War. People are forbidden and there are no sheep or rabbits. But their climate is ideal. The seed catapult has enough range to reach them from a boat offshore. Or I could land and make certain they're properly planted. The seeds will do well on the islands, even if I don't. In a few years they'll become a reserve for natural, non-commercial diversity no matter what happens to me, the last guerrilla gardener.