Complete with its “discreet mark”, an Elizabeth II tumbler cup recently engraved with the coronet and initial of HRH The Princess Margaret, Countess of Snowdon (1930-2002) in preparation for Christie’s sale on June 13-14.

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During preparations for the sale, Christie's and their vendors took the decision to 'improve' some routine silver and jewellery items from the princess's possessions with the addition of the royal crest.

As indicated in the early pages of the catalogue: "The silver lots, whenever possible, have been engraved with the ownership mark of an initial M beneath the Princess' Coronet." Each lot becomes the ultimate sale souvenir when accompanied by a leatherfold containing its own signed, dated and numbered certificate.

A clear indication of where Christie's see their target audience for the sale, a range of workaday pieces of silver and jewellery were engraved, ranging from three Georgian pepperettes used at the Princess Margaret's dining table at Kensington Palace (estimate £200-300) to the modern tumbler cup by George Lowe, Chester, 1958 (estimate £80-120).

In response to ATG questions on this apparently novel marketing exercise, Christie's issued the following statement: "In agreement with the clients, and where possible, a discreet mark was placed on all of the items that are offered for sale to enable the buyers to ascertain in the future the origin of their purchase. This was considered useful in the circumstance of a sale including pieces that can either be easily reproduced or sometimes already in the trade."