The article "Lipreading: Remembering Saartjie Baartman" from The Australian Journal of Anthropology describes it as follows:

On the aftermath of the court case Saartjie Baartman was exhibited in Piccadilly when it was (erroneously) anticipated that the Perceval government would fall and would be replaced by a coalition government headed by Lord Grenvill [sic], which was dubbed by Horace Walpole as the 'Broad Bottom Ministry'. Richard Sheridan, the English playwright and parliamentarian is measuring Saartjie Baartman's buttocks. Grenville is saying, 'Well I never expected Broad Bottoms from Africa, but one should never despair! Mind Sherry, don't let your Fiery Nose touch the Venus for if there's any Combustibles around here we shall be Blown Up!!!' Sheridan answers, 'I shall be Careful Your Lordship! But such a spanker, it beats your Lordships Hollow!!!'