Royal Ascot is tightening up the dress code for both the Royal Enclosure and Grandstand this summer.
The new rules state that hats, rather than fascinators, must be worn in the Royal Enclosure.
And dresses and skirts should be “of modest length”, which is defined as “falling just above the knee or longer”.
In the less formal Grandstand, men are now required to wear a suit with a shirt and tie (the dress code previously stipulated simply, “shirt and tie”) while women’s “midriffs must be covered”.
Strapless or sheer strap dresses and tops are banned and “a hat, headpiece or fascinator should be worn at all times”.
Charles Barnett, chief executive of Ascot, said the changes were intended to restore formality.
He said: “It isn’t a question of elitism and not being modern in a world where there is less and less requirement to dress smartly – far from it.
“We want to see modern and stylish dress at Royal Ascot, just within the parameters of formal wear.”