This is all about fashionable hair styles.
This is the centre of a Bagley 3016 Royal Visit souvenir ashtray, dated, as you will see, October 21, 1937. The Queen is wearing her hair in a style known as a Marcel Wave
After an internet search, I established that the hair style was named after Marcel Grateau, who introduced it in his Montmartre salon in 1872, and executed it by the simple technique of reversing his curling tongs and using the handles. The style rapidly gained popularity in Paris and further afield, and was much imitated.
Then I found a gap of more than six decades. Then references to Queen Elizabeth popularising the style after her accession on December 10, 1936, and particularly after the Coronation on May 12th, 1937.
So, what happened in between? 65 years is rather a long time for a fashion to remain popular. Or did it disappear and then gain a revival? If so, how and why?