Francis Allman was born on 1 November 1780 in County Clare, Ireland, the second son of John and Harriett Allman. He entered the army in 1794 as an ensign in the Queen's Royal Regiment, served in Holland and Egypt and was wounded at Alexandria.
As a commissioned officer he served in the 48th Regiment in the Peninsular war, was severely wounded at Albuera, and was captured and remained a prisoner until 1815. In consideration of his wounds he was granted a pension of £100. 
Accompanied by his wife Sarah Wilson and their three children, he arrived with the 48th regiment on the Minerva in 1818.
He was the first Commandant at the penal settlement at Port Macquarie in 1821. Assistant surgeon of the 48th regiment Abraham Fenton who also arrived on the Minerva with Captain Allman accompanied him to Port Macquarie.
Overton, centre on the map below, was a grant of 2000 acres order by Sir Thomas Brisbane to Francis Allman as a Civil Servant. A reserve of 2000 acres was also set aside for future purchase beside the grant.
A new grant was made in 1827 to conform with new land Regulations. Allman's purchased land was reduced to 640 acres at his request.
Details from the 1828 Census:
Allman, Francis, 48, came free, Minerva, 1818, landholder at Rathluba, Wallis Plains, 500 acres, 130 acres cleared, 40 acres cultivated, 9 horses, 60 horned cattle, 314 sheep
Allman, Sarah, 41, came free, Minerva, 1818
Allman, John James, 16, came free, Minerva 1818
Allman, Francis W.P., 14, came free, Minerva 1818
Allman, Sarah, 12, came free, Minerva, 1818
Allman, Maria, 10, born in the colony
Allman, Harriet, 8 born in the colony
Allman, George L. 6 born in the colony
Allman, Frederick G., 1 and 5/12 born in the colony 
Francis Allman was a prominent settler at Rathluba near Maitland and later held a number of public offices in Illawarra, Goulburn, Campbelltown, Berrima and Wellington before retiring in 1844.
John Kerr McDougall
Overton was sold in 1833 to John Kerr McDougall, the eldest son of Andrew and Elizabeth McDougall, however Francis Allman retained the 640 acres of purchased land of Overton estate.
In 1858 the estate was purchased by Henry Nowland and sold to George Blunt in 1873
Francis Allman died at Yass in 1860. His wife Sarah died at Creek Cottage Yass in 1864.
Obituary of Francis Allman......
Captain Francis Allman was born on the 1st of November 1780 in the county of Clare, Ireland. At the early age of fourteen he entered the army as an ensign and served in many of the engagements during the Peninsular war, at one of which he received a severe sabre wound on his head. He was subsequently taken prisoner, and held in captivity until the general peace, after Waterloo. For his services in the Peninsula he was rewarded with a medal having three clasps. The deceased officer arrived in this colony about forty years ago, as captain of the 48th regiment, and, accepting a commuted pension was appointed commandant at Port Macquarie. He subsequently held similar appointments at Newcastle and Wollongong. From the latter place he removed to Goulburn, where he succeeded Major Britton as Police Magistrate. While holding that office, he came to Yass, with Acting gaoler Doyle as his orderly, to decide on the site for the township. He afterwards was Police Magistrate at Campbelltown and Berrima. Since that time he has lived the life of a retired gentleman; and those who are most acutely sensible of their loss should feel consolation at the recollection that his was an active life, well spent and that the Almighty permitted him to live to witness that which should accompany old age - honour - love - obedience - troops of friends. As a mark of respect to the deceased, the windows of all the shops in the town were half closed on Thursday morning, and have remained so since. His remained will be interred this after noon in the cemetery of St. Clements' Church - Illawarra Mercury 2 November 1860