He was the second son of Arthur Purey-Cust, Dean of York and Lady Emma Bligh, daughter of the 5th Earl of Darnley.

[2] Purey-Cust began to specialise in surveying in 1881, working for two years on HMS Fawn, commanded by Pelham Aldrich, in the Red Sea and East Africa.

[2][3]: 248  While travelling from Plymouth to Sydney in 1889, he observed migrating swallows off the coast of Senegal, which settled on the ship for a while before resuming their journey.

[5] He then returned to England, and spent two years as a naval assistant in the Hydrographic Department before re-joining Rambler in 1897, this time in command.

Surveys were carried out over a wide area, including the West Indies, Africa, and the Red Sea.

His period in office, ending in August 1914, was dominated by deteriorating relations with Germany, and the resulting shift in naval focus towards the North Sea.

Surveys were carried out off the south coast of England, in the southern North Sea, an area characterised by shifting sandbanks, the Firth of Forth, and in Orkney and Shetland.

[3]: 254-258  Purey-Cust was elected a Fellow of the Royal Astronomical Society in 1910,[6] was promoted to rear-admiral in the same year, and made C.B.

[8] They had two children, a son, Arthur John, a naval sub-lieutenant, who was killed in the war, and a daughter Marjorie.