Trainer of Cheltenham big-race favourite says: 'I'll be absolutely gobsmacked if he couldn't win the Gold Cup again'

"I'm giving my innermost thoughts to the Guardian," Nigel Twiston-Davies groans into his phone as he paces up and down a small lounge adjoining his office in a beautiful corner of the Cotswolds. The trainer of Imperial Commander, who won the Gold Cup last year and is the favourite to win the race again at the climax of the Cheltenham Festival on Friday, has turned away from the slow torture of this interview to offer good news to another hopeful racehorse owner.

This is the third telephone call he has taken in less than an hour but, as in his previous two conversations, Twiston-Davies is upbeat when confirming his plans for this week's festival – even if he bashfully admits to the latest owner that he has forgotten the name of the young horse they're discussing. "I'm terrible with names until they run," he murmurs into his mobile.

Twiston-Davies is more adept at speaking his mind. He settles down in his sofa and says, "Right, where were we?", having forgotten whether we had been in the midst of assessing his brusque shyness or why he always wanted to be a farmer. We settle on a suggestion that the strongest lure of farming must surely be the fact that it is a vocation in which interviews are obsolete.

"That's right," he chortles. "You never get interviewed as a farmer. And you're not answerable to anyone. If a horse runs badly you feel so awful for the owner. You think: 'What else could I have done?' If I owned the horse you'd just think, 'Oh well, we'll sort it out.' That's the hardest part of this job."

A more pleasurable aspect is developing a Gold Cup winner. The sheer rapture probably explains why Twiston-Davies is so bullish when stressing his belief that Imperial Commander will win again on Friday. "I definitely would be absolutely gobsmacked if we couldn't win the Gold Cup again."

From such a diffident interviewee that seems an extraordinarily confident statement. "He is supposedly the best horse in the field," Twiston-Davies says. "He won it last year. If he didn't win I'd be like poor old Paul Nicholls last year – absolutely gobsmacked."

Last year Nicholls was at the centre of a media storm as feverish experts debated which of his two horses, Kauto Star and Denman, would triumph. They had won the previous three Gold Cups between them and the stark difference in the horses' characters, allied to their being kept in adjoining stables, made a riveting story – which Imperial Commander stomped all over.

"People got overexcited. They thought it was doing racing lots of good to have this huge competition between two horses – but we ruined the story. Everything went so smoothly. He was always in the right place, jumping beautifully, and he looked good the whole way."

Would he have been "absolutely gobsmacked" if Imperial Commander had lost last year? "Of course. I would've sounded very arrogant if I'd said he was definitely going to win but I thought we had a very good chance."

Why is he so much more upfront this year? "There's nothing definite about it but he's as good as he's ever been. And for me there isn't an outstanding horse there who can take it away from him. He was the forgotten horse last year; he's not forgotten this year."

Twiston-Davies waves away concern that a lingering infection, which meant Imperial Commander could not race against Kauto Star in the King George, might have affected him. He is similarly dismissive of Nicky Henderson's Long Run, who beat Kauto Star in the King George. "I think the old ones, Kauto and Denman, are the toughest to beat because they've proved it. There's a question mark over Long Run's jumping. Cheltenham takes more jumping than Kempton. And reading the papers it seems he's having intensive schooling the whole time. So they must be slightly worried about him, mustn't they? Long Run has got a lot to prove."

The 53-year-old shrugs. "Maybe Long Run's better than we think. Maybe Imperial Commander will get beat. But it will be very hard [to beat him]."

Imperial Commander is already 10 but Twiston-Davies makes it sound as if this is just the continuation of a long Gold Cup saga. Could he even win another one after this year? "Or two," Twiston-Davies says. So Imperial Commander could win three Gold Cups in a row? "Easily. If he wins very well this week, is one more year going to make a big difference? Probably not."

Twiston-Davies might shy away from attention but he could be secretly irked that so much more praise is lavished on Henderson and, in particular, Nicholls. "Well, him and Henderson have got 40 horses running at Cheltenham. I've got 20. The average price of our horses is 20 grand – their average price is 200 grand. Imperial Commander cost 30 grand. You hear that Long Run cost a massive amount – 20 or 30 times more. Kauto Star was hugely expensive."

Does he envy their spending power? "No," he shudders. "I've got quite a lot going on. What must it be like if you've got twice as much?"

It becomes easier to understand why he was on the brink of walking away from training in 2002. On the eve of that year's Grand National, which his horse Bindaree unexpectedly won, Twiston-Davies had resolved to quit for he was swamped by debt. But would he really have walked away from training if Bindaree had not won? "I would definitely have walked away from here. I would have sold up and done something else. I had made the decision we were going to stop and, as it's ridiculous to think you're going to win a National, I was just confused afterwards. It took lots of meetings with the banks to get huge overdrafts to buy this place. Luckily, it's all worked out."

Twiston-Davies is at his most fretful just before Cheltenham – so how much longer can he endure the agony? "If you'd asked me six years ago I would've said 'Five more years …' It's different now. The boys are 18 and 16 and they won't be ready to take over 10 years from now. So I'll go on longer. When the boys are involved it gives you so much more enthusiasm."

His sons, Sam and Willie, are both gifted jockeys. Last year, in the Foxhunter Chase, immediately after the Gold Cup, Sam won on Baby Run, another of his dad's horses. "Sam's win gave me as much pleasure as the Gold Cup," Twiston-Davies says. "It was absolutely great."

He nods his agreement at informed speculation that Sam could become the next superstar jockey after AP McCoy and Ruby Walsh retire. "Sam has great balance and a sharp brain. He's always been very good. Willie's pretty good too."

On Friday, Willie will partner Baby Run in the amateur jockeys' race, again immediately after the Gold Cup. Sam, meanwhile, will ride Sybarite in the Albert Bartlett, just before the big race of the week. Sybarite "could be my next Imperial Commander" and Twiston-Davies clearly expects both horses to win – with the possibility that Baby Run could complete the treble the trainer snatched on the Friday last year. He also believes Khyber Kim, second in the 2010 Champion Hurdle, could be another winner for him today – especially now Henderson has withdrawn the favourite, Binocular, after admitting that he would fail a drugs test for using cortisone.

This is the latest controversy surrounding Henderson. The trainer himself was barred from entering horses in races for three months but James Main, the vet who injected Henderson's Moonlit Path with a banned clotting agent on the day of a race in 2009, has been struck off. Yet Main implied that the illegal substance had been regularly used in racing.

"It's been very tough on the vet," Twiston-Davies says. "He was only doing what he felt was best for the horse. I think he used it in good faith. I don't think they were trying to do anything too crooked."

The trainer laughs awkwardly. "Well, I'm sure they weren't trying to be bent. We'd never used it [the clotting agent] ourselves but I'd heard of it. I had discussed it with vets and we knew it was illegal to give it to horses on the day of a race. Everybody knew – but I suppose they thought it wasn't one that showed up."

He is also downbeat on racing's future. "It's very worrying about the prize money. It's woeful. Something has got to be done. I think the racing programme will have to shrink a bit. We've got to appeal to the wider public so that more people go racing. Maybe there's too much racing for too little money. It would surely help if we had less racing – certainly less bad racing. No one cares about all-weather racing through the winter, but it's giving huge income to the bookmakers who pay the levy."

Will racing have to change to survive? "It will definitely survive. But racing will have to change – or people are going to vote with their feet and there'll be no horses left."

Twiston-Davies is often remembered most for refusing Des Lynam an interview just after he won his first National, but he has always believed that, "the horses should do the talking. You know how crazy the press can be. They'll phone up and ask 'How's the horse?' I want to say: 'Obviously it's dead. That's why I've entered it in the race.' What do you say? 'Well, it's sick, that's why we think it's going to win.'"

The trainer relaxes at last and laughs heartily. We take a walk outside, where the most appealing aspect of his yard is its lack of grandeur. Kauto Star and Denman have their names and all their great victories listed on golden plaques alongside their stables. Imperial Commander just looks happier, as does Twiston-Davies, when the seemingly grumpy trainer cheerfully feeds him a carrot inside his plain old stable.

A carrot, even to a Gold Cup winner, means more than a trophy. "He's not daft, is he?" Twiston-Davies says, looking at the horse that means so much to him.