 Manton discovered many of the works in his collection were what he called Constabiles, rather than works by the master, but Manton took this to be part of the learning process and became close friends with Parris in particular.His friendship with Parris resulted in the offer of a contribution to the Tate's 1987 appeal for funds to acquire Constable's The Opening of Waterloo Bridge, and shortly afterwards a gift of AIG shares, which established the American Fund for the Tate Gallery with an endowment of $6.5m in 1988.Manton never took up US citizenship, retaining his British nationality until his death.