Before the turn of the nineteenth century, the tything of (West) Leigh was made up of a scattered settlement, relying on Havant Thicket, a former part of the Forest of Bere, for its survival. This settlement around Leigh House dates back to the Medieval period, if not earlier. The first mention of a substantial house on the site, or very close to the site of Leigh House, dates to 1767, when on 20th April of that year, Captain Charles Webber R.N., purchased for £340 the ‘reversionary rights’ to a messuage, barn, and gateroom, together with nine acres of land, from Francis Higgins of Middlesex. Higgins was a butcher and had inherited the property on the death of his great-uncle George Higgins in that year. It is highly probable it was the same building that Robert Higgins was paying tax on for on three hearths in the 1665 Hearth Tax for the tything of Leigh.

Charles Webber, who in his naval career had reached the rank of Rear-Admiral, died 23rd May 1783, leaving a widow and five children who were all earlier baptised at Havant. In his will Webber left the small estate at Leigh, along with other land in West Sussex, to his wife Anne. It appears that very soon after his death the property passed to Samuel Harrison, who is recorded in certain records as ‘of Chichester’. A document which is sadly undated but certainly before 1792 refers to ‘the house newly erected by Samuel Harrison.’ This seems to confirm that Harrison had built the house that, after structural alterations by later owners, became to be known as the first Leigh House. A map dated between 1792 and 1800 clearly shows the house and other buildings, including the walled garden, stable block, coach-house, bothy, and the land held by various freeholders and copyholders around Leigh House. Apart from the house, most of Harrison’s other buildings survive, all built in a mellow yellow brick, popular at this time.

It must be remembered that most of the land at Leigh at this time was in the hands of the Bishop of Winchester, who granted the lease of the Manor of Havant to a succession of Havant worthies. These included Richard Cotton of Warblington Castle (in 1553) and later the Moody family. In April 1784 a new lease was granted to Richard Bingham Newland, who as Lord of the Manor began to dispose of parts of the Manor. In 1812 Newland conveyed the Manor of Havant to his brother-in-law William Garrett, who had acquired the Leigh estate in 1800.
From 1792, when Harrison ‘surrendered’ Leigh House to Captain Thomas Lennox Frederick R.N. (1750-1800), the development of the property becomes somewhat clearer. Captain Frederick was the son of Sir Charles Frederick, the Surveyor-General of Ordnance and a cousin of Admiral Sir John Frederick Bt. Frederick’s successful naval career included serving as a captain under Lord Hood at Toulon and Corsica in1792 and serving under Sir John Jervis and Nelson at the battle of Cape St. Vincent in 1797.