Marking significant anniversaries in a monarch's reign

Alexander James Strachan (1774-1850)
Snuff box with profile of George III (1738-1820) 1809-10
RCIN 3893
Rectangular three-colour gold box with canted corners, the hinged lid with a raised, glazed, central reserve containing a silver relief portrait bust of George III within a wreath of thistles and roses, on a blue enamel ground; surrounded by cast and chased foliate scrolls in coloured gold; the sides engine turned and with borders of oak leaves.
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George III was the first monarch to celebrate a Golden Jubilee, marking the 50th anniversary of his reign. The official celebrations began on 25 October 1809. This box appears to be associated with the occasion, the box marked inside Jubilee.
Christmas gift to King George V from Queen Mary, when Prince and Princess of Wales, 1908.