Although Cunningham travelled through here in 1827, it took many years to finally be settled, mainly due to the distance from Sydney, and there still being no easy access from the Moreton Bay area. Patrick Leslie, a young Scotsman, met Cunningham at the home of H H McArthur in Parramatta and decided to investigate this promised land.

In 1840, with a convict named Peter Murphy, Patrick Leslie followed Cunningham’s footsteps to the Darling Downs and was well satisfied with what he saw. On the return trip to Sydney he marked the trail by cutting into the trees. This became known as "Leslie’s marked tree line".

On July the 2nd 1840, the first head station was established by Walter Leslie at Toolburra.

George and Walter Leslie then moved up the river and settled at Canning Downs where they began to build a residence. The three Leslie brothers claimed all the country to the head of the Condamine, including all of its tributaries. One of the conditions of settlement was that all the area must be adequately stocked, so the Leslies had to give up portions to new arrivals, as they were unable to fulfill these conditions. Glengallan, Toolburra, Rosenthal, Maryvale and Talgai were all taken over by new settlers.

The site of the Warwick Township was approved by the NSW Government in 1849 on part of Canning Downs Station, thus paving the way for much closer settlement. The settlement to the east of Warwick became known as the Warwick Agricultural Reserve.