This previously unrecorded mug belongs to a rare group of wares which commemorate Charles II's ascension to the throne in 1660, rather than his coronation of 1661.
The only other closely related example is at Colonial Williamsburg. See John C. Austin, British Delft at Williamsburg (Williamsburg, 1994), p. 101, no. 83, where reference is made to shards of a similar mug found on the Pickleherring Quay site, consequently favouring this attribution. See also Louis L. Lipski and Michael Archer, Dated English Delftware (London, 1984), p. 166, no. 746; and F. H. Garner, English Delftware (London, 1948).
The above example in Williamsburg which was formerly in the collection of Geoffrey E. Howard, sale Sotheby's, 24 July 1956, lot 74 (£320 to Tilley), is illustrated by G.E. Howard, Early English Drug Jars, (London, 1931), pl. 19, no. 66, and was exhibited at the Charles II Loan Exhibition, January 1932, Cat. no. 723 and the ECC Exhibition and illustrated in the Catalogue (1948), pl. 2, no. 9.
Another of similar form, with the more usually found portrait of the monarch within an arch, is in the Museum of London (A.4946) and is illustrated by Frank Britton, London Delftware (1987), p. 123, pl. 72, and p. 86, col. pl. H.