Complex sentence: Regular London seasons alternated with large-scale provincial tours during the 1920s and 1930s, and though during World War II some productions had to be curtailed, the company nevertheless presented seasons in London and the provinces.
Split into simpler sentences: Regular London seasons alternated with large-scale provincial tours during the 1920s and 1930s. Although some productions had to be curtailed during World War II, the company nevertheless presented seasons in London and the provinces.