I have been at a workshop held by the Paul Mellon Centre on the history of the Summer Exhibition. What was clear is how important it has been to the history of British art: a place for professionals and amateurs to show work from the first exhibition in April 1769 (and presumably to sell it, although the mechanism for sales in its early years is unclear); also, the first place where architecture was exhibited, possibly in Europe, as an art form instead of a trade. Landscape was exhibited as a genre from the beginning and the work of women artists, with up to 10% by 180o. Only sculpture was relatively neglected, with no space for it to be displayed until Flaxman was elected as Professor of Sculpture in 1810 and the Model Academy was set aside for sculpture in 1811.
The move of the Academy to its new building next to the National Gallery in Trafalgar Square in 1837 may have made it possible to show larger and more monumental paintings in juxtaposition with the Old Masters next door, as well as having a larger dedicated room for sculpture (I think on the ground floor behind the entrance staircase).
By the 1870s, following the move to Burlington House, the Summer Exhibition was gigantically popular, a mass democratic phenomenon with over 300,000 visitors, showing subject paintings, some of which were frankly kitsch (what Henry James called ‘an extraordinary medley of inharmonious forces’).
The Summer Exhibition seems to have lost its centrality and some of its prestige during the first world war, presumably as a result of the Academy’s increasing conservatism, reduced sales, the rise of an independent art market and the advent of modernism. In 1938, the Selection Committee rejected Wyndham Lewis’s portrait of T.S. Eliot, which led Augustus John, himself an RA, to resign from what he described as ‘the predominant junta of deadly conservatism’.
After the second world war, the RA has gradually reinvented itself and the Summer Exhibition through processes which have yet to be explored.