Frederick Arthur Stanley
aka Lord Stanley of Preston
16th Earl of Derby
(15 Jan 1841 - 14 Jun 1908)
en.wikipedia.org/wiki/Frederick_Stanley,_16th_Earl_of_Derby
He seems to have been a decent man, perhaps more enthused by sport and the great outdoors than with politics as such, despite being the (second) son of a previous Prime Minister, the 14th Earl of Derby. Crucially as regards the Saner scandal, Stanley was Secretary of State for War between 2 Apr 1878 and 31 Apr 1880. And despite this martial job title, he seems to have been pliant towards the representations made by the devious Albert Rollit.