Andy and I meet by the trolleys in Asda car park. As we head towards Vista Tower in the town centre, he tells me about the new peregrines: VDT, a male born in Hemel Hempstead in 2023, and his mate, VSR, a female born in Andover in 2024, both named for their Darvic ring codes. It’s an encouraging development as they are the first pair to establish a territory here during the breeding season, though Stevenage does have resident peregrines in winter.

We start poking about in pavement cracks and drain grates under the 50-metre-high tower block where the peregrines often feed. I spot scurvy grass, buck’s-horn plantain and some matted clumps of fluff; thankfully, Andy’s an expert at reading the remains. He pulls out cinnamon and white scapular and secondary wing feathers of an ash-red feral pigeon; then a cluster of ivory feathers with dark brown barring, plucked from the vermiculated flank of a male teal – evidence of the peregrines hunting waterbirds by night.

It’s no surprise that most of Andy’s extensive feather collection once belonged to hapless pigeons and doves, but I’m astonished that waders are next on the menu. Ducks such as teals are also vulnerable as they fly over, pale bellies lit up by the streetlamps.

I ask why an industrial town in a landlocked county attracts so many waterbirds. Andy reckons they’re moving north through the Stevenage-Hitchin Gap, a break in the Chiltern Hills, on nocturnal migration from their wintering grounds. As they pass over, the peregrines attack from below, latching on and carrying their prey to a plucking post like the one above us.

From his pavement plunderings, Andy has discovered feathers, dismembered limbs, even the occasional head from 46 species, 14 of which were waders, including lapwing, golden plover, jack snipe, whimbrel and an entire oystercatcher. It’s an astonishing, yet grim, tally revealing the diversity of birds taking the Stevenage flyover, unobserved, unless they meet the raptorial talons of fate.

When we look up, there’s the male, preening on top of a nearby tower block. An easyJet plane roars overhead. VDT doesn’t even pause. He looks perfectly at home on his concrete cliff overlooking his adopted urban landscape.