This silhouette came to me with the attribution of Charles Rosenberg, but the bust base/termination does not demonstrate any of Rosenberg’s distinct characteristics. So I think it is more likely to be by William Hamlet the Elder (fl 1785-1816). The McKechnie reference directs us to the main entry in Section 3 – silhouettes on glass which this item is, and was the primary medium for this artist. On page 535 of the McKechnie reference we see that Hamlet used concave glass and backed his work with a slab of plaster, just as this is. The glass is small and suits the dimensions of his work, and the hair is rendered by both brushwork and the needle, the latter being used to show the profile and buttons of the dress jacket. The pigment is very dark. The bust-line suits his work too with the convex/concave combination. There is an almost identical example on page 583 in style of dress, finish, bust line and needle use. So I am confident that this is a lovely example of William Hamlet the Elder’s work.