William Parlby was born in India in what was known as the Bengal Presidency in 1801;[1] his parents were Colonel James Templer Parlby, an engineer in the East India Company (but originally from Plymouth) and Lousia Munt (she was originally from London).

[4] William Parlby died a bachelor in Hubberston, near Milford Haven, Pembrokeshire on 26 October 1881, none of his relatives were named in the will and probate record.

[5] William Parlby was commissioned as a cornet in the 4th (Queen's Own) Light Dragoons on 3 October 1816; he was promoted to lieutenant on 17 May 1824 and then to captain on 28 September 1826.

He was promoted to lieutenant colonel in the 4th Light Dragoons on 30 January 1846 (by purchase),[9] although he only commanded the regiment for seven months.

[19] On home service as a major general he commanded the Cavalry Brigade of the Dublin Division in Ireland, based at Curragh Camp (1860–1861).