Thomas was born in 1852 in Dundalk, Louth, Ireland to Michael Shiels (Shields) and Bridget McConville. He was baptised 12 Jan 1852 in the Dundalk Gaol where he was born while his mother awaited transportation to VDL. Thomas and Bridget sailed aboard the Midlothian, departing 17 Nov 1852 and arriving in Hobart 24 Feb 1853. Thomas was placed into care at the Cascades Female Factory. In Oct 1853 he fell ill, and his mother left the service that she had been assigned to in order to attend to Thomas. He relocated to the Queen Orphan School on 28 Apr 1854. After his mothers marriage to Patrick Power and her subsequent release (24 Jun 1854) Bridget was able to have Thomas discharged into her care (10 Aug 1854). The young family moved to Port Esperence.