Crossley was elected to parliament for
Lowestoft in 1885, as a Liberal. In 1886 he joined the Liberal Unionists and held the seat until 1892 when he chose not to stand again for Lowestoft. In 1897 Crossley stood as a Liberal Unionist in a by-election for
Halifax. He failed that time but stood again in Halifax in the
1900 general election and won the seat. He was appointed
High Sheriff of Suffolk for 1896–97. Crossley was involved in work regarding the National Coronation gift from the people to their new monarch King
Edward VII, and was present as it was awarded to the King two days after the
coronation, on 11 August 1902. For his service, he was invested as a Member (fourth class) of the
Royal Victorian Order (MVO). In November 1902 he was appointed
Paymaster General in the
Conservative government of
Arthur Balfour, and was admitted to the
Privy Council in December of the same year. He remained in this post until the government fell in December 1905, and he lost his seat in the
1906 general election that followed shortly after. Crossley was never to re-enter the
House of Commons. However, in 1916 he was raised to the peerage as
Baron Somerleyton, of
Somerleyton in the County of
Suffolk; Savile Crossley lived in
Somerleyton Hall, as do his descendants. Two years later he was appointed a
Lord-in-waiting (government whip) in the
coalition government of
David Lloyd George. The coalition fell in 1922, but Somerleyton remained as a whip also in the
Conservative administrations of
Bonar Law and
Stanley Baldwin. However, after the first Baldwin government fell in 1924, he was never to hold ministerial office again. ==Military and civic appointments==