Complex sentence: It was whilst on a Australian National tour of Tosca that she had an extramarital affair with Robert Simmons (they were later to marry), this caused a scandal in 1950's Australia so she and Simmons headed for the UK.
Split into simpler sentences: It was whilst on a Australian National tour of Tosca that she had an extramarital affair with Robert Simmons (they were later to marry). This caused a scandal in 1950s Australia so she and Simmons headed for the UK.