Complex sentence: He had a long-standing affair with Wilkinson, and was himself a Labour MP for Peterborough from 1929 to 1931, under the premiership of the first Labour Prime Minister, James Ramsay MacDonald.
Split into simpler sentences: He had a long-standing affair with Wilkinson. He was himself the Labour MP for Peterborough from 1929 to 1931, under the premiership of the first Labour Prime Minister, James Ramsay MacDonald.