‘What on earth are you doing with that banana?’ Mr Clark asked his daughter as he caught her in the kitchen in the middle of the night having come downstairs to check he had locked the back door. ‘And what are these for?’ he added, surveying a carrot, a cucumber and a pot of yoghurt. There was also a ball of string nearby and, which particularly worried him, a kebab skewer. ‘Where have you got this from?’ he said, picking the latter up and placing it on top of the refrigerator.

‘It’s for school,’ said Laura innocently.

‘For school? How is it for school? What do you have to do? Why didn’t you do it earlier?’

‘I couldn’t think what to do. It’s for biology.’

‘Are you sure?’ asked Mr Clark, casting his mind back to his own school days and trying to remember if and when he had had to do anything similar.

‘Yes,’ said Laura. The rest of her answer kept Mr Clark awake that night.

He had not forgotten to lock the door. As he tried to get back to sleep, he wondered if he was becoming paranoid –this was the third time such a thing had happened recently– or if he was turning into one of those people with obsessive-compulsive disorder he had read about in his wife’s magazines, whose lives were blighted by a continuous need to ensure that their taps were turned off, or that the ornaments on top of their televisions were in exactly the right place, or like Tesla, by a fixation with the number three.

Truth to tell, Mr Clark must be one of the most hypochondriac people in Gatshire. Over the years he has ‘contracted’ almost every illness going. Once some public health scare appears in the news, as happens every other week these days, he is the first to confirm the experts’ worst fears. He even goes so far as to quarantine himself after a holiday abroad. He would do this at the airport, but the authorities always insist he goes home, saying something like ‘We understand your concern, but can you imagine what it would be like if everyone went into quarantine after a holiday?’, so he locks himself in his house for a month instead, having stocked up on tinned provisions before the trip. Mrs Clark and Laura escape to stay with the Swifts next door.