May 12th, 1937 is the date coronation of King George VI and Queen Elizabeth, parents of Queen Elizabeth II.
A 1937 Ladies Journal magazine feature with official coronation photo from 1937
George's older brother, Edward VIII abdicated in 1937 in order to marry American divorcee' Wallis Simpson, and George became king, really unexpectedly.
Princess Elizabeth, seen here at age 4 with her father, was not expected to be queen until the abdication made her the next in line for the throne...
This coronation balcony photo is from the Daily Mail UK archives, showing the Princess Elizabeth at age 11...
This is Queen Elizabeth's crown, seen above, which has a platinum frame and 2,800 Diamonds including the Koh-i-nur Diamond which had also been set into the coronation crowns for Queen Alexandra and Queen Mary. Photo from Royal Collection Trust
This is an actual original programme for the coronation which includes a street map of the route as well as description of all the coronation participants so so you could follow along... and below is the official photograph of Princess Elizabeth and Princess Margaret from the program...darling photo...both photos from Time Was Antiques