The best sun hats will add a finishing flourish to any summer outfit. Not to mention protect your face from harmful UV rays. From Grace Kelly and Bianca Jagger to the Duchess of Sussex, every stylish woman knows the power of a good hat. Although designed with functionality in mind, hats will forever be synonymous with the sartorialism of the 20th century – just think of the strong images conjured by bowlers, boaters and Jackie O’s pillbox.