Background
His father was a store-keeper and grazier who had come to Australia with his wife from Ireland in 1837.
His father was a store-keeper and grazier who had come to Australia with his wife from Ireland in 1837.
Born in Yass, New South Wales, Costello was the fifth child of Michael and Mary Costello. The family had settled in Yass in 1851 after selling their store and acquired 1,000 acres (405 ha) in the area. Costello quickly became a renowned stockman.
Costello and Durack both shared a hunger for land and were fascinated by stories of explorers travelling through outback Queensland.
In 1863 the pair met William Landsborough and decided to lead a party to acquire land in south west Queensland. The Costellos along with Durack formed a depot at Warroo Springs in outback New South Wales then later moved north to Mobel Creek.
The Costellos had a son that dies f fever then had a daughter. In 1867 Costello overlanded 200 horses from Mobel Creek through unchartered territory to Kapunda, South Australia in South Australia.
Earning £3000 on the sale Costello returned and acquired the leased to Mobel Springs, a holding of 40,000 acres (16,187 ha).
Costello and Durack moved north again and established both Kyabra and Thylungra Station in 1868 with 100 cattle. In 1869 both drought and depression were taking there toll on the state but Costello continued to acquire lands around the channel country and lightly stock them. The 1870s saw better seasons in the area and buyers moved in to acquire land controlled by Costello and Durack.
Costello himself held leases over 13,000 square miles (33,670 km2) of lands through the channel country of Queensland.
Costello established many stations through the Channel Country including Kyabra, Davenport Downs, Morney Plains, Currawilla and Connemara Stations. In 1877 Costello sold Kyabra and bought a racing stud, Cawarral, near Rockhampton and another property near Galdstone.
But in 1879 he went back to the bush and acquired Lake Nash Station that straddles the Northern Territory and Queensland border. While drought was taking its toll on his coastal properties Costello acquired another 2,000 square miles (5,180 km2) in the Northern Territory.