Complex sentence: He was invited to participate in many group exhibits, among which in 1947 were the "Surrealist Exhibitions" at the Galerie Maeght and the "School of Paris" exhibit in London, his first in that city.
Split into simpler sentences: He was invited to participate in many group exhibits, among which in 1947 were the "Surrealist Exhibitions" at the Galerie Maeght. That year he also had works in the "School of Paris" exhibit in London, his first showing in that city.