From a page linked within the original article:

> The six horseshoes and the sixty-one nails themselves probably date from the 1360's. After being rendered to the Queen's Remembrancer, they are preserved in his Office and, with the permission of the Crown, they are loaned to the City Corporation to be rendered again the following year.

(http://www.cityoflondon.gov.uk/services/education-learning/s...)