Interesting about this is the caption is rather ill-informed as it says "St. Edwards Crown was not in fact used on this occasion".

However, even though it was not actually used for the act of Crowning, St. Edward's Crown (up until 1911 when it was permanently set with jewels) was encrusted with hired stones, and carried in the procession, and placed on the alter in the Abbey.

Even though it was not actually used at the Coronation crown from Queen Anne, right through until 1937, it has always played a powerful symbolic role in the Coronation.

And a s powerful symbol of the monarchy, as it is St, Edwards Crown which acts as a guide in the heraldic depictions of the crown in the Royal Coat of Arms.

http://www.royalcollection.org.uk/collection/31700/st-edwards-crown