The decision to let fireworks off as the runners were at the start for the Derby has caused controversy.
Epsom's colourful display was part of the build-up to the contest, which had a first prize of just over £900,000. As the jockeys completed their preparations pre-race, the fireworks were sent into the sky by the grandstand.
In colours including pink and purple, smoke went up and was blown down the track on the windy afternoon.
In a hectic few minutes, protestors were also removed by police after they gained access to the course.
The group appeared to be holding banners and laid on the turf, around 75 yards from the finish line. Their presence and subsequent action by officers delayed the start of the Derby, sponsored by Cazoo.
It was won in emphatic fashion by the 5-2 favourite Desert Crown, a colt now unbeaten in three starts. While he made a deep impression with fans, social media users were left questioning the call to use fireworks at a racecourse.
Rosie Margarson, the daughter of trainer George Margarson, tweeted: "There was no warning and they were incredibly loud. Even the horses in the stables weren't OK with it. People don't come racing for firework displays they come racing for horses. Horses hate fireworks. Why on earth are we combining the two?"
Another person tweeted: "Whoever thought setting fireworks off near horses was a good idea needs to give their head a wobble."
And a third person added: "Just as well the horses were a long way away from the stands at Epson, not sure if it was a good idea to set fireworks off though, there will be horses in the stables who have heard all that."
On the packed programme of entertainment, five of the Queen's former racehorses paraded at the track and 40 jockeys who had ridden her horses formed a guard of honour. They marked the arrival of royal guests, led by Princess Anne, as the party made their way to their seats.
A spokesperson for the event said: “The Derby is the greatest Flat race in the world and we will always aim to create a special atmosphere.
“The pre-race show was thoroughly tested in advance and both timed and placed with our participants in mind. However, part of constantly striving to improve any major event is to evaluate and we will take all feedback on board in our planning process for next year.”
The Queen, who did not have any runners at Epsom, was said to be avidly following the action on TV. At Worcester, she celebrated a winner when Steal A March came home in front under Nico de Boinville.
