A study of 2,000 adults saw a bright green dress and hat worn during the 2016 Trooping the Colour come second, followed by a purple dress coat donned for the memorial service for the Earl of Snowdon in 2017.
An orange head scarf and dress combo worn during Her Majesty’s tour of the West Indies in 1966 also featured in the top 20 most iconic looks.
Other outfits included a simple black dress, pearl necklace and a bundle of poppies at The Royal Albert Hall for Remembrance Sunday in 2001, and a more casual look of a blazer, knee high boots and colourful head scarf worn at the Windsor Horse Show in 1988.
It also emerged a quarter of adults have felt personally inspired by her majesty’s looks.
And 40 per cent believe the nation as a whole has been influenced, due to her distinctive look (43 per cent), classic style (50 per cent) and ‘simple yet effective’ outfits (42 per cent).
But 38 per cent believe the Queen’s style has evolved to be more colourful over the decades, with the most popular shades to see her in being light blue (27 per cent), yellow (22 per cent) and navy blue (21 per cent).
While 67 per cent feel no one else dresses like the Queen.
The research, commissioned by centre:mk ahead of the Platinum Jubilee, saw respondents predict a silver look for the celebrations, with gold and lilac also proving popular.
Almost half believe the Queen will be remembered for her style, with 45 per cent always looking forward to seeing what she is wearing at a royal event.
Kim Priest, from centre:mk, said: “It’s great to see how many people appreciate the Queen’s unique, quintessentially British style ahead of this year’s Jubilee celebrations.
“The Queen’s style is, and always will be, recognised by the nation – she is best known for her statement hats, handbags, as well as headscarves and her use of colour.
“Inspiring many, her most iconic outfits range from the 1950s all the way up to today, showing that while her looks have evolved over time, it proves that style doesn’t have to vanish with age – it really is timeless.
“The survey shows both her formal and informal looks are popular, from boots being worn at horse shows, to elegant dresses at royal events.
“The Queen has always been confident in her style – she is an inspiration to us all to be comfortable in what we wear.”
The study also saw those polled typically describe Her Majesty’s style as classic (41 per cent), elegant (38 per cent) and colourful (34 per cent).
But over the years, many believe her looks have evolved to be braver and bolder (24 per cent), to fit in with current trends such as popular colours (23 per cent) and to make more of a statement (20 per cent).
While 43 per cent believe pop culture about the royals, such as ‘The Crown’, have altered how people perceive the Queen’s style, with half of 18-24 year-olds personally inspired by her looks – more than any other age group.
A fifth also said the Queen has inspired them to feel more confident with colourful fashion.
Specific fashion trends inspired by the Queen are handbags (49 per cent), brooches (31 per cent) and hats (26 per cent), along with head scarves (22 per cent) and dress coats (22 per cent).
The study carried out via OnePoll saw Kate Middleton (47 per cent) and Princess Diana (41 per cent) among other members of the royal family Brits believe to be style icons – with Prince William (11 per cent) being the top male.
TOP 20 LOOKS WORN BY THE QUEEN
1. Harry and Meghan’s wedding (green outfit and hat with purple detail), 2018
2. Trooping of the Colour (bright green dress coat and hat with white gloves), 2016
3. St Margaret’s Church, Memorial service for 1st Earl of Snowdon, (purple dress coat and hat with black detail), 2017
4. Tour of the West Indies (orange patterned knee length dress with matching headscarf), 1966
5. Visit to Dumfries, Scotland (blue dress coat and hat with red flower), 2006
6. Windsor Horse Show (green patterned head scarf, dark green blazer jacket, cream trousers and black knee high boots), 1988
7. London event (peach sleeveless ballgown and pearl necklace), 1963
8. State visit to Mexico (yellow dress with pleated style skirt and matching turban), 1975
9. Silver Jubilee Year Tour, New Zealand visit (patterned green and white dress with green hat and white handbag), 1977
10. Commonwealth Tour, Kenya (polka dot skirt and jacket), 1952
11. Royal Variety Performance (gold skirt and sequined multi-coloured long-sleeved top), 1999
12. Royal visit to Nassau, Bahamas (navy and white patterned dress with long white gloves and white turban), 1966
13. Silver Jubilee Year Tour, New Zealand Visit (blue and white dress with blue headscarf and white gloves), 1977
14. Her Majesty receiving the Order of St. John’s first Service Medal in Gold (fuchsia pink and purple colour block dress), 2020
15. Windsor Castle cocktail party (floral dress with cropped style jacket and flare skirt), 1959
16. Royal Remembrance (cropped sleeve black dress with pearl necklace and brooch, black gloves and handbag), 2001
17. Pre-wedding dinner for William and Kate (velvet sky blue dress with gold embellished print, gold jewellery, shoes and handbag), 2011
18. King’s Cross Station (textured white jacket and skirt combo with multi-coloured print, black gloves, shoes and handbag), 2003
19. Thailand Tour (orange polka dot dress with matching orange hat and white gloves and handbag), 1996
20. Royal Albert Hall (silver and gold lined dress with white gloves and silver handbag), 2012