It was offered at Sotheby's Sevening sale on December 9 together with an emotive story.
The figure in the work represents Julia, the daughter of the Emperor Augustus who was accused of adultery and treason before being exiled from Rome.
The 4ft 1in x 5ft 8in (1.24 x 1.72m) oil on canvas was previously owned by the former High Sheriff of Derbyshire, Godfrey Meynell, whose great-great-great grandfather had acquired it in 1840.
Meynell, who went to Iraq to act as a human shield in 2003, to protest against the invasion, donated the picture to the United Society, a Christian charity, to raise funds for their relief work to aid Syrian refugees.
Estimated at £100,000-150,000, it drew keen interest at Sotheby's and was knocked down at £550,000 to European dealer who left a commission bid which was sufficiently strong to see off two phone bidders.
The top lot of the night was John Constable's (1776-1837) The Lock, which sold on low estimate at £8m. It was a second version of the painting which the artist had exhibited at the Royal Academy in 1824, a work which sold at Christie's in 2012 for £20m.
The premium-inclusive total from Sotheby's 44-lot evening sale was £22.6m with 29 works getting away (66%).
Meanwhile, Christie's evening sale on December 8 was a more patchy affair with only 26 of the 45 lots getting away (58%). The sale was denied one of its leading lights after a Hans Memling (1430/40-1494) Virgin and Child was sold privately before the sale for a sum above the high estimate of £3.5m, according to the auctioneers.
It also suffered from the failure to sell the watercolour A Hare Amoung Plants by Hans Hoffmaan (1545-91) against a £4m-6m pitch.
The event was led by one of Pieter Brueghel the Younger's (1564/5-1637/8) versions of The Birdtrap which sold at £750,000, below the £1m-1.5m estimate.
A review of the Old Master sales will appear in a future issue of ATG's weekly print publication.
The buyer's premium at Sotheby's and Christie's was 25/20/12%.