The temperatures in the UK might be sizzling today, but it's not deterred glamorous Royal Ascot attendees from pulling out all the sartorial stops.

As one of the highlights of the racing calendar, the prestigious festival at the Berkshire racecourse is just as famous for its fashion as it is for its races - and revellers have continued to keep the fashion stakes high today.

The UK Health and Security Agency (UKHSA) activated amber heat health alerts across southern England, where the heatwave is set to run until next Thursday - and over at Ascot, temperatures are set to reach highs of 29C.

The Met Office said there is a 40 per cent chance of recording the highest-ever June temperature, which stands at 35.6C both in London in 1957 and Southampton in 1976.

But attendees didn't let the balmy temperatures interfere with putting on their best fashion foot forward, and bright, summery ensembles appeared to be the order of the day.

Radiant guests turned the racecourse into a sea of colourful ensembles, while gripping equally vibrant fans and glugging water to help keep cool as they stepped out for the prestigious occasion.

The event's official lookbook this year was curated by menswear specialist Daniel Fletcher, who has previously designed for the likes of Louis Vuitton, JW Anderson and Victoria Beckham.

The guide outlines the dos and don'ts of dressing for the annual event, and for the first time ever, it's also determined its colour of the year - bright tomato.

The festival was founded by Queen Anne in 1711 after she declared Ascot ideal for 'horses fit for kings' and has today become a major social event as well as a sporting attraction.

Yesterday was a match made in society heaven as Hollywood and royalty came together for Ladies Day at Royal Ascot.

Stanley Tucci, 65, who is a regular at royal events and dinner parties, looked just as comfortable in a landau as he travelled to the Berkshire racecourse alongside his wife, Felicity Blunt.

The American actor dressed for the part as he opted for a black top hat and an impeccably tailored suit.

Meanwhile, the sister of Tucci's The Devil Wears Prada co-star, Oscar nominee Emily Blunt, put on a stylish display in a floral dress for the most popular day of the festival, when racegoers pull out all the fashion stops.

Another famous face making their debut in the Royal Family's Ascot procession was the Earl of Snowdon's long-term girlfriend, Isabelle de La Bruyere, as the pair had the honour of riding alongside King Charles and Queen Camilla.

Smiling at the crowds, Princess Margaret's son David Armstrong-Jones, 64, has been dating the French art dealer since 2022, two years after he split from his wife Serena Stanhope after 27 years of marriage.

While the loved-up royal couple attended Ascot together last year, yesterday was the first time Isabelle had joined the royal carriage procession - as she cut a striking figure in a white dress with a black belt.

Travelling behind King Charles and Queen Camilla in the second open-top landau were the Princess Royal, her husband, Vice Admiral Sir Timothy Laurence, as well as the Duke and Duchess of Edinburgh.

Princess Anne's daughter, Zara Tindall, 45, was pictured in the third carriage, riding alongside Princess Zahra Aga Khan, daughter of the Aga Khan, Qatari businessman Sheikh Hamad bin Abdullah Al Thani, and legendary Irish racehorse trainer Willie Mullins.

Senior royals joined thousands of stylish racegoers who put their best fashion foot forward as Ladies Day got underway.

However, the warm weather meant sleeveless dresses and airy skirts were popular sartorial choices - as the UK endures a six-day heatwave with temperatures rising to 27C yesterday afternoon.

Joining the King and Queen in the Royal Enclosure yesterday were Princess Anne, 75, Sophie, Prince Edward, as well as the 2nd Earl of Snowdon, David Armstrong-Jones, who is 25th in line to the throne.

The King's cousin - who owns a bespoke furniture-making business - was accompanied by his long-term girlfriend, art expert Isabelle, less than two weeks after she joined the Royal Family for Peter Phillips and Harriet Sperling's wedding.

Also in attendance today was Princess Zahra, the daughter of the owner of the stolen racehorse Shergar, who recently spoke about the Derby-winning legend's kidnapping in 1983.

The daughter of the Aga Khan, revealed the colt was killed 'in an awful way' and a ransom was never paid to stop the money getting into the wrong hands.

It is 45 years since the big bay with a white blaze won the Derby at Epsom by 10 lengths, a margin which to this day stands as a record for a race first run in 1780.

On the night of February 8, 1983, intruders broke into the Aga Khan's Ballymany Stud in County Kildare and kidnapped the horse.

At the time, the IRA were the main suspect behind the kidnapping, which involved six armed men.

It has been generally accepted that his abductors were ill-equipped to control a thoroughbred stallion, and he was killed shortly afterwards.

On the racecourse today, radiant guests created a sea of colourful ensembles as they stepped out for the prestigious occasion.

Those trying to command attention amongst the crowd of thousands opted for unique garments - including a Spanish-inspired bright red dress - but one guest's extra-large feather hat stole the show.

The wacky, gravity-defying style of hats is permitted in most areas at Ascot, except in the Royal Enclosure.

'A hat or headpiece with a solid base of four inches in diameter is mandatory in the Royal Enclosure,' explained the Royal Ascot website.

'Fascinators are not permitted. Novelty hats (i.e. ones which are excessively oversized, or are promoting or marketing any product or brand) are not permitted.'