As people grow older they tend to display an almost total indifference to their friends’ careers, and certainly Saul does not appear to be concentrating very intently on my replies. A few years back he would have wanted to know everything about the job at the bank: the car, the salary, the prospects for promotion. Now that sense of competition between us appears to have dissipated; he cares more about our game of chess. Stubbing out his cigarette he slides a pawn to C4 and nods approvingly at the move, muttering ‘here it comes, here it comes’ under his breath. The opening has been played at speed and he now looks to have a slight advantage: the centre is being squeezed up by white and there’s not much I can do except defend deep and wait for the onslaught.

‘I’ll have that,’ he says, seizing one of my pawns, and before long a network of threats has built up against my king. The clock keeps sticking and I call for time.

‘What are you doing?’ he asks, looking at my hand as though it were diseased.

‘I just need a drink,’ I tell him, balancing the timer buttons so that the mechanism stops working. ‘There’s never a waiter up here when you need one.’

‘Let’s just finish the game…’

‘…Two minutes.’

I spin round in my seat and spot Felipe serving a table of players. Behind me Saul clicks alight another cigarette and exhales his first drag with moody frustration.

‘You always do this, man,’ he mutters. ‘Always…’

‘Hang on, hang on…’

Felipe catches my eye and comes ambling over with a tray full of empty coffee cups and glasses. ‘Hola, Patrick,’ he says, slapping me on the back. Saul sniffs. I order a beer for him and a red vermouth for me and then we reset the clock.

‘Everything all right now?’

‘Everything’s fine.’

But of course it’s not. The position on the board has become hopeless, a phalanx of white rooks, bishops and pawns bearing down on my defences. I hate losing the first game; it’s the only one that really matters. For an instant I consider moving one of my pieces when Saul is not looking, but there is no way that I could get away with it without risking being caught. Besides, my days of cheating him are supposed to be over. He was always the better player. Let him win.

‘You’re resigning?’

‘Yeah,’ I tell him, laying down my king. ‘It doesn’t look good. You did well. Been playing a lot?’

‘But you could win on time,’ he says, indicating the clock. ‘That’s the whole point. It’s a speed game.’

‘Nah. You deserved it.’

Saul looks bewildered and essays a series of lopsided frowns.

‘That’s not like you,’ he says. ‘I’ve never known you to resign.’ Then, with mock seriousness, ‘Maybe you have changed, Patrick. Maybe you have become a better person.’

Whenever I’ve thought about Saul in the last few years, the process has always begun with the same mental image: a precise memory of his face as I confessed to him the extent of my work for MI5. It was the morning of a summer’s day in Cornwall, Kate and Will not twelve hours dead, and Saul drinking coffee from a chipped blue mug. By telling him, I was placing his life in danger in order to protect my own. It was that simple: my closest friend became the guardian of everything that had happened, and the Americans could not touch me as a result. To this day I do not know what he did with the disks that I gave him, with the lists of names and contact numbers, the Caspian oil data and the sworn statement detailing my role in deceiving Katharine and Fortner. He may even have destroyed them. Perhaps he handed them immediately to Lithiby or Hawkes and then hatched a plot to destroy me. As for Kate, the grieving did not properly begin for days, and then it followed me ceaselessly, through Paris and St Petersburg, from the apartment in Milan to the first years in Madrid. The loss of first love. The guilt of my role in her death. It was the one hard fact that I could never escape. Kate and Will were the ghosts that tied me to a corrupted past.

But I remember Saul’s face at that moment. Quiet, watchful, gradually appalled. A young man of integrity, someone who knew his own mind, recognizing the limits of a friend’s morality. It was perhaps naïve to expect him to be supportive, but then spies have a habit of overestimating their persuasive skills. Instead, having tacitly offered his support, he took a long walk while I packed up the car and then left for London. It was almost four years before he contacted me again.

‘So, do you miss London?’ he asks, pulling on his coat as we swing back out through the revolving doors, heading south down Calle Fuencarral. It’s approaching ten o’clock and time to find somewhere to eat.

‘All the time,’ I reply, which is an approximation of the truth. I have come to love Madrid, to think of the city as my home, but the tug of England is nagging and constant.

‘What do you miss about it?’

I feel like Guy Burgess being interviewed in Another Country. What does he tell the journalist? I miss the cricket.

‘Everything. The weather. Mum. Having a pint with you. I miss not being allowed to be there. I miss feeling safe. It feels as though I’m living my life with the handbrake on.’

Saul scuffs his shoes on the pavement, as if to kick this sentiment away. Two men are walking hand-in-hand in front of us and we skirt round them. It is becoming difficult to move. I know a good seafood restaurant within three blocks – the Ribeira do Miño – a cheap and atmospheric Galician marisquería where the owner will slap me on the back and make me look good in front of Saul. I suggest we eat there and get away from the crowds and within a few minutes we have turned down Calle de Santa Brígida and settled at a table at the back of the restaurant. I take a seat facing out into the room, as I always do, in order to keep an eye on who comes in and out.

‘They know you here?’ he asks, lighting a cigarette. The manager wasn’t around when we came in, but one of the waiters recognized me and produced an acrobatic nod.

‘A little bit,’ I tell him.

‘Gets busy.’

‘It’s the weekend.’

Resting his cigarette in an ashtray, Saul unfolds the napkin on his plate and tears off a slice of bread from a basket on the table. Crumbs fall on the cloth as he dips it into a small metal bowl filled with factory mayonnaise. Every table in the place is filled to capacity and an elderly couple are sitting directly beside us, tackling a platter of crab. The husband, who has a lined face and precisely combed hair, occasionally cracks into a chunky claw and sucks noisily on the flesh and the shells. There’s a smell of garlic and fish and I think Saul likes it here. Using his menu Spanish he orders a bottle of house wine and shapes himself for a serious conversation.

‘Out on the street, when you said you missed not being allowed to go home, what did you mean by that?’

‘Just what I said. That it’s not possible for me to go back to England. It’s not safe.’

‘According to who?’

‘According to the British government.’

‘You mean you’ve been threatened with arrest?’

‘Not in so many words.’

‘But they’ve taken your passport away?’

‘I have several passports.’

The majority of madrileños do not speak English, so I am not too concerned about the couple sitting beside us who appear to be lost in an animated conversation about their grandchildren. But I am naturally averse to discussing my predicament, particularly in such a public place. Saul rips off another chunk of bread and inhales on his cigarette. ‘So what exactly’s the problem?’

He may be looking for a fight.

‘The problem?’

The waiter comes back. Slapping down a bottle of unlabelled white wine, he asks if we’re ready to order and then spins away when I ask for more time. It is suddenly hot at our table and I take off my sweater, watching Saul as he pours out two glasses.