Mould, who has recently published a book called Sleuth: The Amazing Quest For Lost Art Treasures, bought the painting for £50,000 at Sotheby's sale of Early British Pictures on December 4, 2008 where it was catalogued as 18th century English School with a £10,000-15,000 estimate.
He recognised a number of Gainsborough trademarks in the composition when he saw the picture online but a vital clue (ironically something pointed out by the Sotheby's cataloguer) was the similarity of the couple in the foreground to a Gainsborough drawing of the same period in the Louvre depicting the artist and his future wife Margaret.
That the building on the left of the picture is Christchurch Mansion - owned at the time by Claude Fonnereau who lent money to a promising young local artist - added to his conviction.
The view is painted from Christchurch Park looking south towards the civic church of St Mary-le-Tower and the river Orwell.
Research completed before the sale revealed the oil, measuring 2ft 3in x 2ft 11in (68 x 89cm), had been sold for £43 by the Pall Mall auction house Evans in 1824 when it was fully described as a "fine performance" by Gainsborough.
The vendor then was the late George Nassau (1756-1823), who had a particular interest in Suffolk landscapes and whose father Richard Savage Nassau was another Gainsborough family friend. He was painted by Gainsborough in Ipswich in the 1750s when the Nassau family may have acquired View of Ipswich.
Following full authentication by a number of experts, the picture is wanted by the Gainsborough House Museum in Sudbury who are hoping to raise the funds to meet Mould's asking price of £750,000.
Currently it is on display at Mould's Dover Street gallery as part of an exhibition of paintings by the young Thomas Gainsborough timed to coincide with this week's Master Paintings initiative.
The exhibition, that runs until July 28, is titled Tom will be a Genius, the words uttered by Gainsborough's father on seeing his son's first sketches in pencil.
By Roland Arkell