Ritchie began collecting French impressionist and post-impressionist paintings in the 1940s.
Cloisonnism is a style of post-Impressionist painting with bold and flat forms separated by dark contours.
The gift includes his entire collection of more than 50 Impressionist and Post-Impressionist paintings.
After him, the faces concealed in backgrounds of Post-Impressionist painting moved into the foreground of modern art.
Impressionist and post-Impressionist paintings stimulated Wynn's initial interest in the visual arts.
He gravitated toward more conventional works, particularly Impressionist and Post-Impressionist paintings.
On the walls hung reproductions of post-impressionist paintings, chosen, Alleyn felt sure, by Hilary.
For nearly 50 years the museum has maintained total silence about scores of French Impressionist and Post-Impressionist paintings.
Originally accompanying illustrations by Vanessa Bell, its visual organisation has been described as analogous to a post-impressionist painting.
Paul Mellon had previously left the museum more than 900 works, including many Impressionist and Post-Impressionist paintings.