The scion of an Irish parliamentary family, Foster owed his seat in the Imperial Parliament to his maternal uncle Frederick William Hervey, 5th Earl of Bristol, who named a Member for Bury. But for a previous engagement, it might have been his in 1803, when his uncle became a peer.
My Irish affairs are going on but poorly, and therefore for that and other reasons I will, as you say it is not the slightest inconvenience to you, decline coming into Parliament, at least this next election, and shall always feel grateful for that and all your other very many kindnesses and more than kindnesses to me.
... as to settling abroad, putting my dislike to it out of the question I cannot at present afford it, forced as I am to pass some time in Ireland every year. I am well assured that all my losses, not far from ten thousand pounds, have proceeded from my constant absence from my estates.
Foster’s guardian, his father’s cousin John Foster, had insisted on an Irish education for him, but his mother wished him to proceed to Oxford and got her way. He was subsequently the victim of a family tug-of-war in politics. His mother’s liaison with the 5th Duke of Devonshire, whom she married in 1809, placed him in Whig society (he joined Brooks’s Club on 23 June 1804 and was an admirer of Fox), but his mother’s sister was the wife of Lord Liverpool, who became premier in 1812; and it was precisely in that year that he accepted his uncle’s nomination to a seat in Parliament. By character ‘par trop bouffon’, he later boasted that his election cost him ‘a largish sum’.
Foster did not appear on the Treasury list of supporters after his election, unlike his brother. In fact, he described himself as ‘a pretty regular frequenter of the Whig benches’, though he was ‘offered office on more than one [occasion] by Lord Liverpool, if I would leave them and vote with the other side’.
In 1814 Foster accompanied his brother to Paris and remained there until after the Hundred Days. In 1816 he visited his brother at Copenhagen. On 25 Jan. 1817 Lady Holland reported:
Fred Foster has declared he will not vote, some say his mother has persuaded him, others his brother ... others that he is become a staunch Catholic ... In the meantime he is gone today to Lord Bristol’s and the Duke of Devonshire declares he shall beg Lord Bristol to turn him out.
Two Duchesses, 380, 422; Add. 51644, Lady Holland to Horner, 25 Jan. 1817.
He voted for Catholic relief on 9 May 1817 and paired with opposition for the right of magistrates to visit political prisoners, 18 June, but was listed in the majority favourable to the suspension of habeas corpus, 23 June. He had previously assured his aunt that he was pledged not to vote in opposition ‘whenever Lord Liverpool or Lord C[astlereagh] were personally concerned’. Lady Liverpool’s retort was, ‘My dear Frederick, placed where Lord Liverpool is and feeling as he does, he is personally concerned in everything’.
When the Whigs were in power, in 1831, Foster would have liked a baronetcy, but he waived his pretensions in favour of his brother.