At the 1904 election, he won the East Fremantle seat in the Legislative Assembly from the conservative incumbent, Joseph Holmes, achieving a 26% swing.
[1] At the election the following year following the failure of the Daglish Ministry, Holmes won the seat back with a 20-vote majority.
Angwin filed a petition against his return, and on 12 April 1906, the seat was declared vacant by the Chief Justice of the Supreme Court on the basis that 26 votes were incorrectly recorded.
[2] Holmes appealed, but was unsuccessful, and on 24 October 1906 a by-election was called, at which Angwin won 71.4% of the vote against another opponent.
He left England on 25 March 1933, and chaired two Royal Commissions on wheat in 1935 and 1938, and presided over the Rural Relief Trust in 1936.