To the right of the initials there is a cypher which is similar to the personal monogram of Queen Henrietta Maria, wife of Charles I. In Figure 1 (below).
(1) the H and superimposed M accords with a frequently used cipher on the Queen's documents in the National Library of Wales330;
(4) the encircling crown is related to the crown cipher used by Van der Doort for the marking/branding of Charles I's paintings331
Monogram (1) is also used in a c.1640 inventory of Charles I's picture collection to mark miniatures, or paintings. The monogram, alongside five entries, may denote that the works either belonged to, or were in the possession of the Queen332.
In the Royal Collection there is a miniature of Queen Henrietta Maria by John Hoskins. On the case of the miniature is a device (3) in white enamel. This monogram shows the development of a crown over the letters. (The drawing is copied from Van Der Doort's inventory)333.