Many bad things were said about grays at the time, but then as now, the heart of the English objection to the grays comes down to this: they outcompete the reds. They are simply better at the job of being squirrels. Britain’s taste for unfettered competition has always been fitful, and how much it tipped the playing field in favor of the reds varied. At first, the job of controlling grays was largely left to the private landowners who had first imported them. But as the grays pushed up England, the government got involved. Beginning in the 1930s, it offered half a shilling per gray-squirrel tail, eventually raising the bounty to 2. The arrangement was politically popular but flawed: farmers and ranchers had a good reason to kill gray squirrels but no reason to eliminate them entirely. In the late ’50s, the government called off the program after estimating that there were more grays than before. From then until the early 2000s, and especially during the Thatcher-Major years, when the British government re-enthroned competition in Britain, the gray was left alone, and it extended its range, at the expense of the red, from the top of Wales to the Scottish border.

Redesdale and Parker didn’t tell me there was going to be a gray squirrel in the trunk of their car. We were in the gift shop at the south end of the Northumberland national park, near the town of Hexham. It was the day after the meeting in Sue Southworth’s living room, and Redesdale had promised to take me to see a place where he had cleared out grays and the reds had come back in. He and Parker had been busy. The gray toll was now 2,353, up 21 from the day before.

Redesdale sat with Parker, who was dressed in the exterminator outfit he wears: toxic-green sweater and pants. With them was a local groundskeeper. They were looking at maps of Northumberland, seeing how the war was going. Redesdale explained the Red Squirrel Protection Partnership to the groundskeeper. “So you on board for being part of the killing team?” he asked the man.

“Aye.”

“Brilliant.”

Redesdale has a strained relationship with the main red-squirrel protection groups: they need him; they call him sometimes when they get a gray squirrel sighting over their toll-free hot line; but he takes up a lot of their time. Carri Nicholson, the project manager for S.O.S., told me that she thinks of Redesdale as a kind of naughty child. “If you can’t play nicely, you’ll have to go to your room,” she said she tells him.

Most of all, S.O.S. officials say they wish Redesdale would trap squirrels only where reds and grays are currently competing, in the north, rather than in areas more toward the south, like Hexham, which are considered a lost cause. “Lord Redesdale wants to get rid of grays all over Northumberland,” Peter Lurz, an ecologist at Newcastle University, told me. “I think it’s a tall order. You’re dealing with a rodent that has two litters a year.” He added, “Unless you remove 70 percent of the rodents you’re just making room for the litters.” He suggested that Redesdale’s efforts had only “psychological impact.”

Lurz was an architect of the plan for the red-squirrel reserves that the government established last year: 16 in the north of England. He based his plan on the observation he made in the field that because the red squirrel is smaller than the gray, it can live on less food. It does fine, for instance, in a conifer forest, without rich acorns and beechnuts; in such an environment the grays will leave for a better habitat elsewhere. As it happens, the large conifer forests in Britain are in the north, where the reds remain. According to the initial government plan, S.O.S. would monitor the red and gray squirrel populations in the refuges. The Forestry Commission would replenish conifer trees that make the habitat desirable for reds. And the government would establish buffer zones along the perimeters — places where it would encourage landowners to kill any grays they found. The reserves seemed a fitting solution for postcolonial Britain. The gray would keep what it had won. The red, like the British themselves, would content itself with a small homeland in return for peace.

The refuges might have held the grays back, at least for a while, but as they were being created, it became clear to Lurz that any contact between grays and reds — even the minimal amount occurring in the refuges — was going to be catastrophic. This is because grays have yet another weapon in their arsenal: they carry a virus, to which they appear to be immune, that kills the reds. The disease, called squirrelpox, is awful to see: it turns the soft tissues around their eyes, ears and nose to sludge. Death comes within two weeks. Last summer, Lurz, having carefully studied squirrel-population records, calculated that where infected grays mixed with reds, the reds very quickly disappeared. “It was too much of a coincidence,” Lurz told me. In fact, he noted, “dirty” grays took land away from reds at roughly 20 times the rate healthy grays did.