They called in to the shop to buy chocolate and a pile of postcards for Fran to send to her family in the south – when the weather allowed for post to go. The talk there was all about the storm. The middle-aged woman in her hand-knitted cardigan leaned across the till. ‘Any news on the boat, Jimmy?’ And when he shook his head: ‘I can’t see it going tomorrow and the last of the bread’s gone now. Just as well I bought in lots of dried yeast. The beer’s on the low side too. Let’s hope folks have stocked up for themselves.’

Further north again the settlements petered out. There was a rise in the land and Fran could see the road winding away, the hill and the airstrip on one side and an area of flat grassland on the other. To the right the sloping bulk of Sheep Rock, jutting into the sea, which gave Fair Isle its instantly recognizable shape from Shetland mainland and from the Northlink ferry.

‘What’s that?’ Fran had stopped and turned her back to the wind. She’d thought she was fit but this was hard going and she was glad of the excuse to rest. She pointed to a wire-mesh cage built over the wall. It was shaped like a funnel with a wooden box at the narrow end.

‘A Heligoland trap. It’s where the wardens from the field centre catch the birds for ringing. There have been naturalists here since the fifties; they started off in some wooden huts near the North Haven. The place was set up by a couple of guys who were prisoners of war. Apparently they dreamed of coming back and founding a centre for studying birds and plants. When the North Light went automatic there was a huge fund-raising effort to convert it to a state-of-the-art field centre. In the spring there are organized courses for botanists. This time of year it’s taken over by birdwatchers. Sometimes the Isle seems full of people with binoculars and telescopes chasing rare birds.’ Perez paused. ‘They’re kind of obsessed.’

‘How does it work, the people in the field centre and the islanders? Does everyone get on?’

‘Generally. We all grew up with a centre on the island and everyone agreed with the lighthouse conversion – it’s so far from the rest of the houses that you can’t imagine ordinary folk wanting to live there. It provides business for the shop and the boat and the post office. There’ve been a few complaints in the past about visitors breaking down walls and flattening crops when they get onto folks’ land, but one storm like this could do just as much damage as a horde of birdwatchers. Maurice and Angela have been there for about five years. Folk seem to like them OK.’

‘I thought your mother said the place was run by someone called Jane.’

‘Jane’s the cook. Very good and scarily efficient. The island’s started to have its parties there because the food’s so good.’