After graduating from Radcliffe College (Harvard University) with a degree in Fine Arts, Mary Ann moved to London for a year and it was there that she started buying Lear's watercolours. Although not an artist herself, she appreciated the process of painting and was attracted by his sketches, complete with the commentary he frequently added and the occasional reworking that occurred. She loved to travel and appreciated that his unfinished works gave such a sense of the areas he was drawing.
She purchased her first Lear, El Koorneh, in 1958 and Lear's comment in it, "oh, the flies!" always made her laugh. It hung above her desk. Her acquisitions gradually picked up steam and in 1966 alone she bought four. Some works by Lear she purchased from Agnews Gallery in London and others from galleries in New York; Durlacher Brothers and Davis to name a few. Her brother Nat Dexter bought for her some of the more polished works, but since they usually weren't her favourites, they were generally hung in less prominent locations in the house.