On 9 April 1851 he pleaded guilty at the Old Bailey in London to forging and uttering three bills of exchange totaling £1,247/0/2 (£1,247.01) and was sentenced to fourteen years transportation.
[5] Horrocks departed Woolwich on 23 October 1851 and Portland on 2 November 1851 on board Marion,[6][7] arriving at Fremantle on 31 January 1852.
At Lynton his duties were to attend the medical needs of all officers of the civil establishment, ticket-of-leave men and sick natives in the area.
[10] Horrocks received a conditional pardon on 19 April 1856, and set up as a storekeeper and postmaster at Wanerenooka (Northampton), while continuing to provide for the community's medical needs, free of charge.
In 1859, Horrocks took up 40 hectares (100 acres) of land, and, with the help of George Shenton Sr, began to develop a copper mine which he named "Gwalla".