Before he was of age, St. John Mildmay entered Parliament on his father’s interest for Winchester, the latter having realized his ambition to sit for the county. This was an honour he did not himself aspire to when his father died in November 1808, nor did the ministerial party wish to push him.
Mildmay had reinforced his interest at Winchester and in 1812 secured a fellow dandy as his colleague in the representation, after a contest. He repeatedly toasted Lord Grey, it seems, at Western’s election for Essex.
Mildmay’s wife had died in childbed in 1810 and despite confident reports in 1813 that he would be married again, probably to Lady Monson or, at ‘Beau’ Brummell’s insistence, to Miss Thayer ‘the Exhibition Hebe’, he had not done so. In October 1814 he eloped with his wife’s sister the Countess of Rosebery after their liaison had been detected. This he did, according to John William Ward, who encountered him at Rome soon afterwards, ‘wholly under the influence of vanity’, which ‘made him lose half of one of the finest estates in England at play, and impair one of the finest constitutions in England by drinking ... He is a very handsome man, and not without a certain quickness that may be mistaken for talent.’ Henry Brougham, Mildmay’s counsel, ‘beat down’ the damages against Mildmay to £15,000, after fearing they would be twice that amount. In 1815 the couple were married in Württemberg by royal licence and lived obscurely there.
Mildmay’s demoralization was gradual. His dearly bought wife left him for a Canningite. Their three sons entered the Austrian service. In 1840 Lord Broughton was astonished when he met
the gay and handsome Lothario whose follies made so much noise in my younger days. He is now fat and overgrown, with no pretensions to good looks; but he is lively and talkative, and, having seen a good deal of the best society in Italy—Milan principally—has many agreeable stories to tell.
Overwhelmed by financial difficulties, he shot himself, 17 Jan. 1848. He had feared arrest and imprisonment, and a verdict of ‘temporary insanity’ was reached.
