Tried: 13 Jan 1790, Old Bailey, Middlesex. Sentence: 7 years transportation. He arrived in NSW aboard the Active in 1791.
On 26 January 1799 he appeared before the Judge Advocate’s Bench relating to money owed for labour done by Hugh McMurphy and the matter was settled. Then on 13 Jul 1799 William’s name appeared on a list of Vagrants and vagabonds and their sureties, he was discharged to Mr. (L or Z) Clark servitude. William was again in front of the the Judge Advocate’s Bench under suspicion of stealing a quantity of live poultry from John Palmer Esquire, he was ordered to work in the gaol gang. 
On the 14 Oct 1799 he was ordered to Norfolk Island when “sufficient proof not appearing to commit the following persons implicated in this and other robberies, they now ordered to be closely(?) confined in the gaol gang and sent to Norfolk Island as thieves –namely William Osborne, William Slater, John Ladley, John Clarke, John Bryan”. William name does appear on the shipping records for HMS Reliance to Norfolk Island in Nov 1799 embarking on the ship at Port Jackson on 30 Oct 1799, however he returned with the ship to Port Jackson disembarking on 23 Dec 1799 at Port Jackson.
The July 1801 NSW muster has William Slater, per Active, expired, residence in Sydney, off Stores. William was charged on 15 February 1800 under suspicion of stealing bags of meal? from Simeon Lord, and remanded for the next Justice examination. After which at some time he travelled to Norfolk Island.
1802 William Salter: Norfolk Island, male convict, on stores for 365 days, so William’s arrival on Norfolk Island is pre 1802.
On Norfolk Island William formed a relationship with Mary SMITH, Convict, Britannia 1798, age 19 years. Crime: Felony, Tried: Exeter Devon, October 1797. Sentence: 7 years transportation. She arrived on Norfolk Island pre August 1802, and she was first with Thomas McCARTY. Mary eventually lived with William Slater from 1804.
1805 William Slater: Salt Boiler, Male Convict, on stores.
1806 William Slater: Male Convict, on stores.
They left Norfolk Island for VDL aboard the Estramina in May 1808, with her three children (one child from Thomas McCarty relation the other two with William Slater).
1811 William Sleater: Abode Hobart.
1811 Mary Smith: Abode Hobart.
1818 William Slater: Abode Hobart, off stores.
1818 Mary Slater: Abode Hobart, off stores.
William died 20 December 1830 Hobart.
 The Proceedings of the Old Bailey Ref: t17900113-61.
 Minutes of Proceedings of the Judge Advocate’s Bench, 8 Dec 1798 – 5 Mar 1800, SRNSW, X767, NRS 3397, SRNSW SZ767, pp, 44; 94 and 100.
 Minutes of Proceedings of the Judge Advocate’s Bench, 8 Dec 1798 – 5 Mar 1800, SRNSW, X767, NRS 3397, SRNSW SZ767, p. 121.
 Reliance shipping musters AJCP, ADM36, PRO Reel 7007, p.73.
 Minutes of Proceedings of the Judge Advocate’s Bench, 8 Dec 1798 – 5 Mar 1800, SRNSW, X767, NRS 3397, p. 144.
Includes extracts from Norfolk Island Baptisms, Burials and Marriages 1801 – 1806