His father was a widower when he married Lydia Flower and there was an elder son, William Henry, born 1855 in Ulverstone Registration District, Lancashire, England to John and Sarah (née Blackhall), who died in 1856.

In 1881, he moved to Melbourne where he joined the printing firm of McCarron, Bird & Co.[1] Harry Diddams first attempt to enter local politics came in January 1907 when he opposed the sitting alderman in the South Ward of the Town of Toowong where he was living in Ashton Street.

[5] In 1916, Diddams' role on Council included representing the town on the ANZAC Commemoration Executive[6] charged by the State Government with the organisation of a suitable public remembrance of the events of the previous April.

An excerpt of the speech is below: “By the kindly act of Nature our city is blessed with a site of supreme beauty, while our near environment of mountain, river, and shore, forms a very paradise of delight—a wonderland of promise.

Diddams (2 December 1923) [7]In January 1929, Harry sailed 'home' to New Zealand aboard the Aorangi to visit his sister, Mrs Fred Kenderdine, of Remuera.