He is having dinner on the terrace of a boutique hotel in the Algarve. England are playing Tunisia on a giant screen in the corner and have taken an early lead. Most of the other diners are England fans but there are no requests for his thoughts or attempts to engage him. It's as if he had never played the game; as if none of it had ever happened.
Tunisia have been awarded a penalty. He watches, impassively, as Ferjani Sassi finds the net and is mobbed by happy team-mates. An Irish woman, who has been chatting to his partner, Jo, raises a glass of wine and salutes him from across the table: "You're the only one here who knows how that feels, Tony."
"Yeah," he smiles.
And yet . . .
The month is June, 1990. He is sharing a hotel room in Cagliari with Andy Townsend on the eve of the game against England. It's their first World Cup but they travel second class. There is no TV or air conditioning in the room. They are lying on two beds watching a slow ceiling fan. It feels like a scene from Apocalypse Now.
The England game is the biggest of his career. He plays well in the 1-1 draw but is dropped for the third game with Holland after a below-par performance against Egypt. "That's the thing about the World Cup," he says. "In a (qualifying) campaign you might go four or five games without scoring, but go two games without scoring in the World Cup and you're out of the team.
"I remember swapping shirts with Gianluca Vialli after the quarter-final in Rome where we had both started as subs. I'd gone into that tournament as Ireland's leading number nine; he'd gone into the tournament as the leading number nine for Italy but had lost his place to Toto Schillaci.
"I remember shaking his hand and thinking: 'He's experienced what I've experienced; he's suffered what I've suffered.' Because whatever Vialli had done in his career, that tournament would always be about Schillaci. And when Niall (Quinn) scored against Holland, it was the same for me.
"That's what I was thinking about the other night when (the woman on the terrace) said, 'You're the only one here who knows how it feels.' Because it's a great thing to have played in the World Cup but it was overshadowed by the pain of being left out. I regret so much about those (two) World Cups.
"I look back now and I want to kick myself: 'Why the hell wasn't I the fittest I could have been?' I was fit in '94 but unfortunately got injured, but '90 will always be a regret for me: I just wish I had been more disciplined professionally."
And yet . . .
The weeks and months that followed have never left him. There was a ticker-tape parade when the team returned to Dublin and a euphoria captured memorably in his book, Full Time:
"In the seven months since we had qualified for the finals, the country had been ravaged by the most contagious fever since the foundation of the state. Football fever. Blotched in green, white and orange, we could not have been greeted more fervently if we'd won! And on that hot summer afternoon in June, there was no greater celebrity than to play for the team that Jack built. We were Masters of the Universe. Kings.
"In London, I could go shopping or take the Tube or walk the streets in almost total anonymity. In Dublin, I was recognised by every man, woman and child. Six thousand people turned up to meet me one afternoon when I arrived to open a fete in Tipperary. I thought the engagement would take about an hour at most but I was absolutely mobbed - 'Sign this, Tony', 'Well done, Tony' - and by the end of the day had to beg to get away. They just couldn't get enough of me. And everywhere we went it was the same."
"The day we came back from the World Cup in '90 was the longest day of my life," he says. "Have you ever been cuddled all night?"
"Cuddled?" I ask.
"I don't mean by a woman, I mean everywhere you go."
"No, I can't say I have."
"It's knackering," he says. 'Everyone you meet wants to grab you and talk to you or buy you a pint or have a dance. You do it for an hour and it's okay, but you do it for three and you'll do anything to escape. I've never really been comfortable in the spotlight. I like it in small doses but I don't know how the real stars deal with it."
"Fame?" I ask.
"Yeah. Andy Townsend told me a story once. He was at an Eric Clapton concert and was invited backstage with Jackie (his wife) to this VIP room. There are loads of people there but he spots (Mick) Jagger and (David) Bowie chatting in the corner and Jackie wants him to get something signed: 'When will you ever have this opportunity again?'
"So he grabs a pen and a bit of paper and has almost reached them when this woman cuts across him and puts a request in first. And Jagger just launched into one: 'Can't you see I'm fucking talking!'"
"This is to the woman?" I ask.
"Yeah, and Andy immediately turned around. And I thought he was out of order when Andy told me first but I understand it now. I'm sure being Mick Jagger is fine for a day but I don't know how I'd cope on a regular basis."
And yet . . .
A week after the team returned to Dublin, he decided to travel to Westport with his wife, Sarah, and infant son, Michael, to explore the home of his late grandfather, Michael Joseph O'Malley. It was a warm and lovely Sunday in June and after a quick visit to the town they sought directions to a beach and were sent to Silver Strand.
He had never seen anything like it.
"We're driving down this tiny road and an old man with a stick and a million sheep is coming the other way. It felt like we were in a time warp," he says. "We get to the beach and throw down some towels and there are about six or seven cars with people sitting around all listening to the hurling on the radio.
"And I know it was hurling because I had to ask about it. And nobody recognised me. 'Isn't that weird,' Sarah said. 'You've just come back from the World Cup and we've had all that euphoria in Dublin and there isn't one person here who knows who you are.' It was as if we'd landed on a different planet but it was lovely. I liked being left alone. I didn't want to be in the limelight."
And yet . . .
The thing that really amazes him almost 30 years later is that the affection has endured. He was invited to a World Cup preview event in London recently by the Republic of Ireland Soccer Supporters Club. Three days earlier, he had written a column in The Times about a tumour on his brain that requires major surgery and the response was extraordinary when he was introduced to the crowd.
"It was lovely. I was quite emotional," he says. "Then the questions started and we had a real laugh and by the end of the night they were singing my name and we were doing the hokey-cokey and they were singing my name . . . 'T-O-N-Y C-A-S-C-A-R-I-N-O' . . . 'T-O-N-Y C-A-S-C-A-R-I-N-O' . . . It was like we were back at World Cup 90, as if time hadn't changed."
And yet . . .
Eighteen months have passed since he first noticed the symptoms - a hissing noise in his left ear that he decided to ignore. Then he lost the taste buds on the left side of his mouth and noticed a tingling in his cheek and a growing deafness in his left ear. Jo kept bugging him to get himself checked but there were bills to pay and games to analyse and he kept pushing it back.
Then his balance was affected and he fell down the stairs.
His doctor sent him for an MRI and a tumour the size of a golf ball was revealed. The good news was that the lump was benign; the bad news was that it would have to come out and required major surgery. "I go into hospital on July 19 but I'm trying not to think about it," he says. "There's a chance I'll lose my hearing and that my speech will be slurred but I've spoken to some people who have had the operation and have all come through it fine."
"So no fear?" I suggest.
"There's a fear of the unknown when you're sitting in front of the surgeon and he's giving you the bleakest picture of things that might go wrong. And I daydream a lot about lying on the hospital bed and how it will feel waiting to go in. Everyone says that the only way to get through it is to be positive but you can't help what you think sometimes.
"And what I've been thinking about is Jo, and my sons, and my daughter, and my mum, and my sister, and will I see them again? That's over-dramatic, I know, but it's there. And it's the little things . . . Teddy (Sheringham) sent me a message when he met you at Augusta. I saw Paul Kimmage out in Augusta mate. He says he's worried about you, like we all are.
"And that got to me," he says. "Because that's just not Ted."
"No, it's not," I concur, battling the lump in my throat. "He doesn't do worry."
But Cas wouldn't be Cas if he didn't see the funny side: "I must owe the fucker money," he laughs.
World Cup 2018
Ruben Loftus-Cheek starting for England in a World Cup game would light a beacon for all the young Premier League players who are blocked on the path to first-team action by clubs who would rather buy a solution than support their home-grown talent.