Wilsonn was the youngest son of Robert Wilsonn and his wife Jemima Bell, daughter of John Bell, haberdasher, of Colston Bassett. His father was a printer and stationer of Birchin Lane and Lombard Street London and receiver of duties on windows. He was apprenticed to his father and freed by redemption on 3 May 1774 and went into partnership in the bookbinding and stationery business with his brother Richard in 1775.
He was baptised at Street Mary Stoke Newington on 9 July 1752 to which parish the family had moved after the destruction of their home in Exchange Alley by fire in 1748. Wilsonn also acted as deputy to his father as receiver of window duties. In 1783 Wilsonn was a Freeman of the Stationers Company, and also became common councillor for the Langbourne ward, which office he retained until 1790.
In October 1784 he wrote to William Pitt as "a sincere admirer of the present administration" offering to take on the receivership of the new window tax - as efficiently "as I now do the old window tax account".
He was given instead receivership of the commutation tax for Middlesex and also wheelcarriage, servants, horses, waggons, carts, shops and assessed taxes. He gave evidence to the Privy Council on gold coin in 1788.
In 1791 he was trading as a stationer on his own account and was in livery by 1792. In 1792 wrote to the prime minister, begging him to preserve the gold standard.
In 1795 he signed the London merchants’ declaration of loyalty to Pitt’s government.
He was in various business ventures in the City of London and was listed as an East India Company stockholder in 1795. Foreign the loyalty loan of 1797, he subscribed £25,000 as a resident of Enfield and £25,000 as a merchant at Change Alley. He was also a governor of Christ’s Hospital.In 1803 was a director of Globe Insurance.
One of his fellow directors was Miles Peter Andrews with whom he was connected through the Pigou family.
He did not contribute to debates and all his known votes were for the ministerial side. In 1816 and 1817, he opposed Catholic relief.
He resigned the seat in 1818. Wilsonn lived at Dome House at South Bersted, near Bognor Sussex.
He died there at the age of 77.
Wilsonn married Elizabeth Nixon (died 6 July 1835) of Lombard Street on 24 June 1774. They had no children.
5th United Kingdom Parliament]
He was a member of the committee that sponsored the Enfield infantry in 1794. Andrews was Member of Parliament for Bewdley and on his death in 1814, Wilsonn was elected Member of Parliament for Bewdley.
