William Chaffey (the younger) was tried at New Sarum (Salisbury) Assizes, Wiltshire on 19 July 1817 and sentenced to 7 years transportation for picking pockets. (1) He was admitted to the Justitia Hulk at Woolwich on 24 October 1817 and transferred to the convict ship Tottenham
on 25 April 1818 for transportation to New South Wales. He was 22 years old at the time of transportation.  His occupation was later recorded as a cork cutter.
William Chaffey continued his life of petty crime after arrival in New South Wales, managing to escape from custody and roam the bush for a few months in 1826. Over the first twelve years in the colony his crimes escalated from absconding and petty thieving to burglary each with increasing penalties until at last he was sent to the most dreaded penal settlement of the day - Norfolk Island.
On first arriving in New South Wales in 1818 he was sent to Parramatta and assigned to service from there. In 1823 at Airds he committed a robbery and was sent to Port Macquarie.
By 1825 he was again in trouble with the law when he escaped from an Escort with three other men.......
Sydney Gazette 12 December 1825:
Notice - The following persons who stand charged with felony, and were committed to take their trial at the Supreme Criminal Court have escaped from the Escort going from Liverpool to Campbelltown - William Chaffy alias Davis; Thomas (or James) Boyd; and George Gambol, free by servitude; and William Puckridge, a native of the Colony....... All Constables and others are required to use their utmost endeavours to apprehend the said men, they being dangerous characters; and any person found harbouring them after this Public Notice, will be prosecuted with the utmost rigour of the law.
Together with James Boyd, Chaffey made his way to the Hunter River district:
From The Australian 26 April 1826:
Two men named Chaffy and Boyd who had been apprehended at the Coal River and forwarded for examination before the Bench of Magistrates at Liverpool, underwent an examination on Saturday. These men are supposed to have been concerned in the robbery of Mr. Jamison's. One man has been convicted of this robbery. Mr. Jamison having sworn to his identity. Some people think that he was mistaken in the person of the man; and the above two have been ordered to appear before the Bench at Campbelltown in order to give Mr. J. an opportunity of seeing them. These men were under commitment on a charge of stealing some ducks. They escaped from a Campbell Town constable as he was conducting them to gaol.
In July 1826 the Australian reported.....William Chaffey alias William Davies, and James Boyd, were charged with assaulting Jacob Cooney, a constable, and rescueing themselves from his custody. Jacob Cooney swore — that the two prisoners were delivered into his charge some time ago, under a warrant to convey them to Liverpool Gaol ; that when on the road, the prisoners threw him down on his back, and having rescued the handcuff key from his pocket, handcuffed him to a tree ; they then made their escape, but offered no further violence. They were each sentenced to six months to the House of Correction, to hard labour.
In making their way to the Hunter River area, Chaffey and Boyd would have had little chance of remaining at large. The district was in high alert after the depredations of the infamous Jacob's Irish Brigade
just a few months previously. For the first time horse patrols had been sent to the area and settlers slept with guns at the ready.
William Chaffey was discharged from gaol in January 1827. In November 1828 he was sentenced to twelve months in an iron gang for having stolen property in his possession.. He was sent to No. 3 iron gang at Newcastle and absconded from there in March 1829. He was re-captured and sent to the Lower Branch to complete his sentence.
In 1830 he was convicted of burglary in the house of James Stirling Harrison in Pitt Street, Sydney and a sentence of death recorded was passed against him. He was sent to the hulk at this time, (Sydney Gazette 20 May 1830
) and probably to Norfolk Island from there.
He was at Norfolk Island in 1834 and took part in the prisoner rebellion in that year. Later at the trial presided over by Justice Burton, William Chaffey was found guilty of being an accessory before the fact in the case against ringleader Robert Douglas. 
Twelve prisoners were executed on Norfolk Island after the rebellion; however although Chaffey had been found guilty he escaped execution.
William Chaffey was admitted to Sydney gaol for an unknown crime in 1839.
1. The Salisbury And Winchester Journal and General Advertiser of Wilts, Hants, Dorset, and Somerset.
2. UK, Prison Hulk Registers and Letter Books, 1802-1849 - Ancestry
3. The Australian 8 July 1826
4. Decisions of the Superior Court of NSW. R v. Douglas
5. Account of the trial Sydney Gazette 27 September 1834