The 1960 Royal Wedding of Princess Margaret & Anthony Armstrong-Jones. Anthony Armstrong-Jones (later becoming Lord Snowdon) was Duffy's colleague at Vogue studios. He told Duffy where to position himself on the day to get the best shot and said he would look out of the carriage when they reached that point on the journey. He kept his word and this photo was published in Vogue shortly after. Lord Snowdon was not only a talented photographer but an active campaigner for the rights of the disabled.
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