Astley Onslow Thompson was born in Wales in 1865, the eldest of nine children who survived past infancy. He attended England's prestigious Rugby School, immigrated to Australia at the age of 18 and initially worked as a public servant.

In the late 1880s, under the wing of his Onslow cousins at Camden, Astley became manager of Camden Park when dairying was about to become vital to the estate's ongoing prosperity. He studied dairying in England and Europe with Elizabeth Macarthur Onslow and returned in 1889 to restructure agriculture at Camden Park.

Elizabeth as owner and Astley as manager worked together to establish an innovative dairying complex. It included share-farming, a network of creameries, butter production and the sale of whole milk to the Sydney market.

Astley was a man of many talents and achievements. He was on the Board of CSR and the Commercial Banking Co. of Sydney, chairman of the Camden AH&I Society and a lay preacher.

He helped to raise the Camden Squadron of the NSW Mounted Rifles in 1892 and later commanded the regiment, which became known as the 2nd Australian Light Horse. When World War I broke out he joined the army in August 1914 as a Lieutenant Colonel and was posted to the 4th Battalion.

Astley took part in the ANZAC landing on 25 April 1915 and was killed in an attack on a Turkish position the following day. He was 'Mentioned in Despatches' and is buried in the 4th Battalion Parade Ground Cemetery at Gallipoli, Turkey.