The 3in (8cm) gold locket had a lock of pale coloured hair on the obverse tied as a bow set alongside a seed pearl and gold anchor. On the reverse, a simple tied spray of auburn hair set with seed pearls.
It also featured, in the centre, the initial N, and 1st Aug. 1798, the date of the Battle of the Nile and a month before Nelson was introduced to Emma Hamilton.
The auburn hair on the reverse of the locket closely matches other known surviving hair of Lady Hamilton.
The following year Nelson (made Duke of Bronte by Ferdinand of Naples) insisted on the duel initials NB, so the locket may date from the first months of his enduring love affair with Lady Hamilton.
At the Salisbury sale on January 27, it sold for £44,000 (plus 19.5 per cent buyer's premium), nine times the top estimate.
The buyer was London fine antique jewellers Sandra Cronan.