Ruby Walsh said the protests which delayed the start of this year's Aintree Grand National created a great deal of "tension" at the race-track, which may have contributed to horses getting more "excited" than they might have otherwise.
The 2023 edition of the famous race was delayed due to a protest from animal rights group 'Animal Rising', with protestors attempting to scale fences to enter the racecourse, some doing so successfully before being hauled away by police.
When the race was eventually started, there were eight fallers at the opening two fences, considerably more than at recent renewals. One horse, Hill Sixteen, tragically died after falling at the first fence, the third fatality of the three-day festival.
The race was eventually won by Corach Rambler for the second successive year.
In an interview on BBC Radio 5, Hill Sixteen trainer Sandy Thomson labelled the protestors "ignorant" and said the delay had "unsettled" everyone and that the horses were "buzzed up" before the start.
BHA chief executive Julie Harrington acknowledged on BBC Sport that "a direct parallel" could not be drawn between the protests and the death of a horse, though argued "it certainly cannot have helped."
Animal Rising spokesman Ben Newman responded, saying: "We disrupted the race for two reasons. One was to stop the race to stop a horse dying. Two, to have a conversation about our broken relationship back to animals."
Reflecting on the delay on RTÉ's Game On, Ruby Walsh, who twice won the Grand National aboard Papillon in 2000 and Hedgehunter in 2005, said people could feel the "tension" at the venue.
"You look at Aintree, it's a huge course. The Grand National course is two miles around, and you've the perimeter around that. You'd 75,000 racegoers. Security was tight, there was a huge police presence.
"I suppose what added to it, and what people are saying about some of the horses probably getting a bit more excited than they usually would, and maybe jockeys too.
"I don't mind the delay, because there could be a delay at the start of any race, for a horse spreading a shoe or a horse getting loose going to the start. Delays can happen.
"But this created a really weird atmosphere in Aintree on Saturday. It was tense, it was uptight. It wasn't a boisterous start to the Grand National. The 15 minutes or so for the delay, when people didn't know what was happening, it just created tension. And a lot of tension. And you could feel that everywhere.
"And that didn't add in a good way to the race. There's no way it could have. I don't think it would add in a good way to any sport. Not just horse racing. It was disappointing to watch it all."
Animal Rising, who signalled their intention to disrupt the race beforehand, released a statement afterwards alongside a petition calling for the Grand National to be banned, saying "we have the power to end cruel horse racing in the UK forever."
Walsh defended the group's right to protest but argued that it had to be peaceful.
"Animal Rising were behind the protest. Everyone has a right to protest. Everyone has a right to their own beliefs.
"But I do feel it has to be done in a peaceful way. And I'm not sure storming a racecourse was a peaceful way. It's not in my eyes anyway."