Admitted to the bar in 1899, Barwell built a successful legal practice where he specialised in defending murder suspects[1] and became a prominent figure in the Adelaide Establishment.

[3]: 3  He forced the funding of a £5 million rehabilitation program through parliament and recruited a brilliant American railroad executive, William Alfred Webb, to lead it.

[6] Barwell lost the 1924 election to the John Gunn led Labor Party[2] and, after briefly acting as Opposition Leader, resigned from state parliament, seeking a seat in the Australian House of Representatives with a view to becoming Prime Minister.

Realising that a move into the lower house was now a forlorn hope, Barwell resigned from the Senate to accept the posting of South Australian Agent-General in London.

He served in that position until 1933, helping to prepare opinion for the Ottawa Agreement and for the closer collaboration of the various parts of the British Empire.

[7] After the completion of his term as Agent General, Barwell remained in London, entering into various business interests, before eventually returning to Adelaide in 1940,[8] where he unsuccessfully stood for pre-selection in his old seat of Stanley.

Growing increasingly deaf, Barwell served as Deputy Chairman of the South Australian Housing Trust for fifteen years until his death in 1959 from cerebrovascular disease.