Richard Jackson (1818-90), the illegitimate son of the 4th Marquess of Hertford and Mrs Agnes Jackson, was raised in Paris by his grandmother from the age of six.
The 4th Marquess never acknowledged his paternity, and in 1842 Wallace took his mother's maiden name. Until his father's death he acted as the 4th Marquess's sale-room assistant and adviser.
In 1870 he inherited his father's collection, the apartment in the rue Laffitte, the chateau of Bagatelle, and the estates in Ireland. He soon also bought the lease of Hertford House from the 5th Marquess of Hertford.
While Paris was besieged by the Prussians and then devastated by the uprising of the Commune, Wallace won a considerable reputation through charitable works and gifts to humanitarian causes. In recognition of his philanthropy he was made a baronet in 1871, just after he had married his mistress, Julie Castelnau, the mother of his thirty-year-old son, Edmond Richard.
In 1872 he took up residence in London, bringing with him from Paris many of his finest works of art. While Hertford House was being converted to accommodate them (1872-5), much of the collection was exhibited at the Bethnal Green Museum where it was a popular sensation, visited by many thousands of people. Unlike his father, Wallace took an interest in the responsibilities that his wealth brought him, particularly in Ireland. But the circumstances of his birth and the refusal of his wife and son to become anglicized meant that he was never fully accepted in English society.
After the death of his son in 1887 he returned alone to Bagatelle where he died three years later. In general Wallace's taste in paintings, furniture and porcelain was similar to that of his father, but he did not buy so many works of this kind. Where he principally differed from the 4th Marquess was in his fondness for medieval and Renaissance works of art.
In 1871 he purchased the collections of European arms and armour and medieval and Renaissance decorative arts formed by the comte de Nieuwerkerke, Napoleon III's Director of Fine Arts. In the same year he also bought a selection of the European arms and armour collected by Sir Samuel Rush Meyrick and in 1872 the vicomte de Tauzia's early Italian paintings and illuminated manuscript cuttings.
He also acquired many superb miniatures and gold boxes, though he bought very few works of art in the last fifteen years of his life.