This was the second of three voyages of the Lord Sidmouth bringing convicts to New South Wales the others being in 1819 and 1823. The Lord Sidmouth was the next convict ship to leave Ireland for New South Wales after the departure of the Prince Regent in September 1820.
Surgeon Thomas C. Roylance
Thomas Roylance joined the Lord Sidmouth on 28th June 1820. 
On 15th July at Deptford Captain Richard Moore of the 45th Regiment, commander of the guard was embarked with his wife. 
A detachment of the 1st Royal Scots embarked as guard for the convicts, 31 in number accompanied by 13 women and ten children. The wife of Private Liddy gave birth to a child soon afterwards. On 30th August Private Faulkner was punished with 275 lashes for insubordinate conduct and disrespect to his Commanding Officer.
Cove of Cork
On the 20th they dropped down from Deptford and anchored at the 'Long Hope' below Gravesend under orders to proceed to Cork. On Saturday 22 July they anchored in the Downs and on Sunday proceeded down the Channel. They were off the Isle of Wight on 25th July and at anchor at St. Helens on 28 July 1820. They moored in the Cove of Cork on 3rd August 1820. 
Before the arrival of the prisoners Thomas Roylance issued a similar set of instructions for the care of the convicts that he had previously on the Hadlow.
Convicts From Kilmainham Gaol
The Freeman's Journal reported on 9 October 1820 -
This morning between 3 and 4 o'clock the embarkation of convicts from Newgate and Kilmainham Jails took place. The Jailers and Sheriffs of the city and County were in attendance and got the unfortunate victims to crime doubly bolted on jaunting cars and, with a strong escort of Horse, proceeded to the Pigeon House Dock, where they were shipped on board the brig Betsey, bound for Cork. Their numbers and counties are as follows:
Co and City of Dublin from Newgate...26
Antrim from Kilmainham...15 Armagh from
Kilmainham..7 Down from Kilmainham..9
Kildare from Kilmainham...2
King's Co. from Kilmainham...13
Longford from Kilmainham...1
Leitrim from Kilmainham..3
Louth from Kilmainham...12
Meath from Kilmainham 7
Roscommon from Kilmainham 10
Westmeath from Kilmainham 7 ........All males.
On 7th October 1820 94 male convicts from Waterford were received on board. On 10th October another 58 men were received from Cork. On 12th October 12 more were received and four returned to shore.
They got under weigh on 9th November 1820.
The Lord Sidmouth arrived in Port Jackson on Monday 19 February 1821, a voyage of 107 days.
One hundred and sixty prisoners arrived under the care of Thomas C. Roylance. All were reported to be in excellent health, although Roylance wrote that from touching at no Port and some of the prisoners being debilitated and aged and from the births occurring on board it became necessary to expend the wine and medical comforts. 
Thomas Evans, a private belonging to the Royals, who was coming out to join the recently arrived detachments of that Regiment, by the Lord Sidmouth, drowned himself between the Heads as the vessel was entering the Harbour. The Sydney Gazette reported that he had deserted in Ireland, which prevented his being with the detachment that came by the Prince Regent, and had become entangled in pecuniary embarrassment:-those unpleasant circumstances pressed upon his mind, and are supposed to have induced him to commit the rash deed that has untimely deprived him of existence. Thomas Evans had been sentenced to 150 lashes at a Court-martial for leaving his detachment. The punishment took place on the Lord Sidmouth while the vessel was still in Cork.
It was reported that the prisoners brought by the Lord Sidmouth were landed at the King's Wharf on Friday 23 February in the forenoon, and after being inspected by His Excellency the Governor, were directed to be distributed according to their various employments and avocations.
2). Convict Edward Farrell was executed for stealing a sheep in August 1821 just six months after arrival....Edward Farrell, William Sheehan and Patrick Fox, were indicted for stealing a sheep, the property of Gregory Blaxland, Esq., and Thomas Styles and Barbara Styles, were indicted as accessories and receivers. Edward Farrell and Barbara Styles, Guilty. Sheehan, Fox and Styles were acquitted. Sydney Gazette 18 August 1821.
3). Return of Convicts of the Lord Sidmouth assigned between 1st January 1832 and 31st March 1832 (Sydney Gazette 5 July 1832).....
Michael Reynolds. Labourer assigned to Henry McDermott at Sydney
 Bateson, Charles, Library of Australian History (1983). The convict ships, 1787-1868 (Australian ed). Library of Australian History, Sydney : pp.344-345, 383
 Ancestry.com. UK, Royal Navy Medical Journals, 1817-1857. Medical Journal of Thomas Roylance on the voyage of the Lord Sidmouth in 1821. The National Archives. Kew, Richmond, Surrey.