There can be few more diverse challenges in racing than the 30 fences of the Grand National and a straight bolt up the Rowley Mile, but success in both events had a similarly devastating effect on the Irishman's emotions.
As Stack contemplated his first Classic victory, he brushed his eyes and answered in a faltering voice. 'I shouldn't be like this,' he mumbled. 'But it was the same with Red Rum at Liverpool. It's that sort of day.'
The pattern of the race cannot have helped the trainer's equilibrium. Drawn in stall one, Las Meninas's jockey, John Reid, had no option but to hold his mount back as the action boiled around him. Up front, Dance To The Top, Relatively Special and the favourite, Mehthaaf, each took a turn in the vanguard as Reid, riding his filly for the first time, found himself in a position that would have tested Houdini.
'I had plenty of horse underneath me, and it was a matter of just being patient and waiting for the field to break up,' he said. 'But it seemed to go on a long time. I couldn't have sat there much longer.'
Once a fissure appeared, Las Meninas wriggled free, and joined the leaders. The problems then were narrowed down to two horses, the Lanfranco Dettori-ridden Balanchine and Coup De Genie, ridden by Cash Asmussen. Las Meninas and Balanchine surged past the post in apparent unison but the photographic evidence showed that Las Meninas had won, as they say in these circles, by the thickness of a cigarette paper.
For Reid, it was a third Classic, following Dr Devious's Derby in 1992 and On The House's victory in this race 12 years ago. 'I've won the 1,000 Guineas before but it seems like a lifetime ago now,' he said. 'These days are magic.'
A neck behind the principals was France's Coup De Genie, completing a one-two- three without either a British- trained horse or British rider. Mehthaaf was fourth and her jockey, Willie Carson, gave the reason that riders should deliver more often. 'They were better horses,' he said in explanation for his filly's eclipse.
Perhaps even more discomforting for the home team than the foreign domination was that the runner-up was prepared over the winter in the warmer environment of Dubai. Putting horses in a hothouse to encourage their development is not a new idea, but the experiment has never been conducted with the vigour of Sheikh Mohammed, Balanchine's part-owner, who has nurtured 50 thoroughbreds in the Gulf this winter.
Perceived wisdom has it that his filly, who is trained by the Dubai champion trainer, Hilal Ibrahim, is six weeks ahead of her rivals in terms of maturity. She ran like it, and there is now solid evidence that Britain's early-season Classics may become easy prey for horses from the Middle East.
Sheikh Mohammed and Robert Sangster, Las Meninas's owner, greeted each other warmly as the photo-finish print was being processed. Sangster had less to lose as the developer was being poured out. He bred Balanchine and received a sizeable sum when selling her to the Sheikh last year. Now the members of her family which he retains have had their value enhanced.
The greenhouse effect has not been lost on Sangster and he intends to import two-year- olds to Britain from his Australian string. But, for now, he himself can bask - in the achievements of Las Meninas.
The filly is named after a painting by Velazquez. Yesterday, their values were brought much closer together.
Photograph and report, page 37