In 1874 he joined the Bank of Australasia and was posted at Creswick and it was here that he made friends with David Temple and William Spence, two pioneers of the trade union movement in Australia.

[2] In 1881 he was transferred to Townsville to open a branch of the bank there and later supervised its expansion to other centres in North Queensland and by 1885 he was working in Sydney as a sub-inspector.

He was employed there for ten years but clashes with James Burns over administrative procedures and salary levels led to his resignation and Lennon then established his own mercantile and auctioneering business in Townsville.

Then at the 1899 Queensland colonial election, representing the Labour Party, he unsuccessfully stood against his former employer, Robert Philp, for the seat of Townsville.

[2][10] Once Lennon took the role of Lieutenant-Governor he immediately appointed another fifteen Labor men (known as the suicide squad) to the Council, much to the disgust of the "old Guard" members such as Arthur Hawthorn and Patrick Leahy.

[11] When the President of the Legislative Council William Hamilton died in July 1920, Lennon claimed that he had to leave Queensland and travel to New South Wales which in turn made Pope Alexander Cooper the Administrator of the Government.

The next year the Council, now with an overwhelming Labor majority, voted itself out of existence with the Constitution Act Amendment Bill.