Richard was not blind to the possibility put to him by his father, when he relayed some of Clem’s stories, that they were exaggerated, if not entirely invented. Reluctantly, he concluded that this might well apply to the old chap’s single most startling claim: that he had saved the two eldest daughters of Tsar Nicholas II from murder by an anarchist in Cowes in the summer of 1909. As Clem told it, the Grand Duchesses Olga and Tatiana went shopping in the town during a visit by the Russian imperial family to Cowes regatta that year. Clem stopped, disarmed and arrested a gun-wielding would-be assassin who was in the process of entering the rear of a millinery shop where the two girls were idly debating a hat purchase. This brave and timely intervention earned Clem the personal thanks of the Tsar. ‘Pleasant fellow,’ said Clem of Nicholas. ‘Probably too pleasant for his own good, though, considering how things turned out for him.’

As it transpired, the story was too good to be true. Richard took himself off to the County Records Office in Newport after school one day and looked up the Isle of Wight County Press for the relevant week. The Tsar and Tsarina and their children had indeed been in Cowes in August 1909, or, more accurately, off Cowes, in the moored imperial yacht. And the two eldest Grand Duchesses had definitely gone shopping in the town. But no assassination attempt thwarted by a PC Hewitson was mentioned. The four days of the imperial visit had passed without incident.

Richard was too embarrassed to challenge Clem on the point, but Marty was not. And Clem had a ready answer. It took no great effort for Richard to retrieve a clear memory of the old man as he was that day: tall, bald, lean and stooping, eyes twinkling, mouth curling in a smile beneath his yellowy-white handlebar moustache, studying Richard across the tiny front parlour of his house, the room smelling of pipe smoke and stewed tea, sunlight streaming through the window on to the brightly patterned tiles flanking the fireplace and the framed photograph above it of Clem on his wedding day back in 1920, when his moustache was lustrously dark and his back was ramrod-straight.

‘You’ve been checking up on me, boy? Well, we’ll make a detective of you yet.’ The laugh merged with a cough. ‘It comes down to politics, see. They couldn’t have it said the Tsar’s daughters weren’t safe on the streets of England. So, it was hushed up. I should have had a formal commendation by rights. But that’s the way of the world. Might be best if you didn’t put it in your project, though. It could still be a state secret for all I know.’

Richard did not believe him, much as he wanted to. But absolute veracity was hardly to be expected from such an inveterate yarn-spinner as Clem Hewitson, whose claims of secondment to Special Branch during the Second World War and missions abroad he was still not free to talk about were as tantalizing as they were dubious. Certainly his son, Marty’s father, Denis Hewitson, had no time for the old man’s ‘romances’, as he called them. Denis ran a ship-design business in Cowes which he took very seriously, as he did his golf and his garden. His outrage when pop festival-goers slept on his lawn one summer’s night in 1969 kept Richard and Marty – and Clem too – laughing for weeks. Richard’s father was equally strait-laced, as befitted a deputy county surveyor. At heart, Clem was younger than either of them. That plus the distant reach of his memory – he often recalled watching Queen Victoria’s funeral cortège, the mourners led by the new King Edward VII, and his cousin the Kaiser, when the grand old lady’s body was conveyed from Osborne House to the waiting royal yacht Alberta on a sparkling winter’s afternoon in 1901 – made him an object of fascination as well as fondness.

The boys eventually outgrew that fascination. They naturally saw less of him after they left for Cambridge in the autumn of 1975, though no return to the Island was complete without at least one visit to the old man. He never accused them of neglecting him. Somewhere, Eusden had a photograph taken by Gemma of the three of them – Richard, Marty and Clem – standing together on the Parade in Cowes, with the QE2 visible out to sea, cruising up the Solent towards Southampton. Clem had just passed ninety then, but looked as spry as ever.

Eusden remembered borrowing a photographic history of the Island from Newport Library once in an attempt to imagine the Cowes of Clem’s youth. The town had a pier then; women wore long dresses and wide-brimmed hats; the men boaters and high-collared jackets with waistcoats. The sun seemed always to be shining, pennants fluttering from the massed yachts on regatta days, watched by parasol-twirling ladies. Ironically, Eusden would need an equivalent volume for more recent decades to re-imagine his own youth now: the ice-cream days of summer, when he and Marty took buses to distant parts of the Island, supplied with sandwiches and orange squash by their mothers, free to roam and explore. Alum Bay, Tennyson Down, Blackgang Chine, Culver Cliff: the places were all still there; but the times were gone, beyond recall.

Over the years, Eusden’s visits to the Island had become fewer and farther between. His sister Judith still lived there. She and her husband ran a garden centre at Rookley. Physically, his mother was still there too, vegetating in a nursing home at Seaview; mentally, though, she had left long since. Judith occasionally rebuked him for neglecting his nephew and niece. He found it impossible to explain to her just how painful it was for him to return to the sights and sounds of his childhood and adolescence. ‘When you went off to Cambridge, I thought you’d be back for Christmas,’ she said to him in a soulful moment after their father’s funeral. ‘But you know what, Richard? You never did come back. Not really.’

When Clem Hewitson died, in the summer of 1983, aged ninety-six, Marty was in the Middle East. He did not attend the funeral. Neither did Eusden. He had often regretted his absence, though he doubted Clem would have held it against him. The old man was as hard to offend as he was toforget.

As the train drew out of Waterloo station, Eusden gazed up at the attaché case lodged in the luggage rack above his head. The mere sight of those initials – CEH – had plunged him into helpless reminiscence. This had made him wonder if Marty wanted whatever the case contained to reconcile himself to his past in some way; to make peace with the times and the places – and the people – he had effectively fled from. It was hard to conceive of any other reason why he should be so eager to retrieve it. But there might be such a reason. Eusden realized that. And in two and a half hours, he would find out whether there was or not.

The Belgian countryside and the outskirts of Brussels had looked grey and bleak through the train window. But there was nothing to be seen of the outside world on the concourse of Bruxelles-Midi station. Eusden was in a man-made realm of platform buttresses and garishly lit retail units: fast food and quick fashion amidst the tidal swash of travellers. There was nothing to be seen of Marty either, at the spot where he had told Gemma he would be waiting: Sam’s Café, adjacent to the escalator down from Eurostar Arrivals. This did not worry Eusden unduly. The train had got in ahead of schedule and Marty had never been on time for anything in his life. Eusden changed a tenner into euros at the Western Union next to the café, bought himself a coffee and sat down at one of the tables out front.

Ten minutes later, he was beginning to grow a little anxious. Marty was not a well man. It was easy to imagine some disaster had overtaken him. Eusden decided to check the arrivals screen for trains from Amsterdam.