On his return to Sydney Leslie married Catherine (Kate), daughter of Hannibal Hawkins Macarthur, at Parramatta on 9 September 1840. His best man at the wedding was Stuart Donaldson. On 2 July 1840, the first head station was established by Walter Leslie at Toolburra. Walter and George Leslie then set about building a residence at Canning Downs. Although the three Leslie brothers claimed all the land to the head of the Condamine River, including its tributaries, they were forced to give up most of the claim to new arrivals because of the requirement that all land claimed had to be adequately stocked.