There was a pause.

‘Have you told the others?’ asked Grace, and Kate sensed a defensive tone in her voice.

‘No. I just came to you. I haven’t . . .’ Kate suddenly deflated. Then, a rumbling sound in the distance. It grew steadily louder: it was mechanical, an engine. A tractor appeared on the brow of the hill, making its way across the field towards them. Behind it was a large boom that stretched out several metres over the crops, and from the entire length of that boom emanated a light mist. It drenched the crops and rolled across the air, a continuous hissing discharge, and as the tractor grew closer, a distinct chemical smell began to filter through to the garden.

Grace stared, apprehension contorting her face. She shot an agitated look at Kate, unsure of what to say, what to do. Kate could begin to taste something foul in her mouth and she involuntarily recoiled. The shouts from the boys as they played their game of football were still audible above the tractor – just. The machinery continued to approach, getting louder and ever closer.

‘Get in, get in!’ shouted Grace suddenly, running towards her children in panic. They stopped kicking the ball, bewildered by the look on their mother’s face. She grabbed each of them by the hand and pulled them back into the house, Kate bringing up the rear.

The patio door slammed shut, and Kate saw that Grace was shaking. They watched as the tractor drove past the perimeter of the field and the spray meandered gently across the garden. Then, a few minutes later, as quickly as it had appeared, the tractor vanished, back down the hill in another loop around the field. It would only be a matter of minutes before it returned.

‘Ah, Mum, I was about to score!’ complained John.

‘It’s bath time,’ said Grace quickly. She looked up at Kate. ‘So, I’m afraid I’m going to have to ask you to leave.’

Kate started. ‘Of course.’

It was a swift goodbye and Kate took the train straight back to London. As it raced past the innocent-looking, glorious yellow fields, she thought about Grace, her twins. She thought about the terrible thing she had just imparted and felt guilty. But she knew she hadn’t read all those reports wrongly. She also had the sense that she had only touched on the tip of the iceberg.

‘I don’t understand,’ said Tim, pouring Kate a cold beer as she sat at her computer. ‘How can farmers be allowed to spray this stuff? Surely it’s illegal?’

‘You’d think, eh? But look – it’s here,’ she said, pointing at the screen. ‘There’s this rule the regulators use – is it safe according to the “Bystander risk assessment”? In other words, they assume that there’ll only be occasional, short-term exposure to these chemicals, just a few minutes, say. They don’t take into account if you live next door to a farm where it’s being sprayed regularly. Sometimes more than twenty times in a season.’