English School, circa 1665

This picture would appear to conflate a number of portrait types. It relates loosely, in reverse, to a three-quarter-length portrait of the sitters, previously ascribed to Jacob Huysmans and now associated with Sir Peter Lely (Agnews Exhibition 1935, Heinz archive, National Portrait Gallery). The portrait of Catherine is drawn more specifically from a three-quarter-length portrait by Lely in which she is depicted in an identical blue dress and ermine-lined mantle, seated in a shell back chair (R.B. Beckett, Lely, London, 1951, p. 38, no. 71). The portrait of Charles is unusually informal; the main Lely types show him in Garter robes, or armour. The head type compares quite closely with John Michael Wright's three-quarter-length portrait in the National Gallery, London.
There is an armchair with a similar scallop-shell back, probably designed by Francis Cleyn (1582-1685), chief designer at the Mortlake tapestry works, dating to circa 1625, in the Victoria and Albert Museum, London. However, Lucy Wood, Senior Curator at the Victoria and Albert Museum has suggested that the idea for the chair in this painting is likely to come from an engraving rather than an actual chair.