Mortimer has filled this small sheet with action, depicting in the top right, Apollo and Artemis destroying the children of Niobe, in the bottom a hermit-like saint, dressed in rags and contemplating a holy book, with a band of banditti suggested on the left. On the verso, there is a rapid black chalk sketch of a hanged man.
The depiction of Apollo and Artemis in the act of destroying the children of Niobe recalls the work of Mortimer’s friend, Richard Wilson and may offer supporting evidence to a statement by Henry Angelo:
‘Mortimer and Wilson, though dissimilar in their general habits, were great cronies at this period: so much so, indeed, that Mortimer painted for his ingenious colleague the figures in the clouds and those on earth, in his famous picture of the Niobe… Nothing, to be sure, could be more like mere daubing than the figures of Wilson’s painting, generally.’
Whilst the idea that Mortimer had any involvement in Wilson’s depictions of Niobe has never been taken seriously, this drawing points to his awareness of the finished composition, the figures being close to those added by Placido Costanzi to at least one version of the painting. Mortimer did alter the figures in another of Wilson’s historical landscapes, his Meleager and Atalanta. Whilst the present drawing does not confirm Mortimer’s involvement with Wilson’s painting, it suggests that his friendship with Wilson and Thomas Jones meant he was actively thinking about the figural groups in their historical works.