Complex sentence: Royal guests present were Princess Anne, Queen Elizabeth The Queen Mother and Princess Margaret, Countess of Snowdon; it is stated that Prince Charles was invited, but did not attend, due to another commitment which occurred on the same day as the wedding.
Split into simpler sentences: Royal guests present were Princess Anne, Queen Elizabeth The Queen Mother and Princess Margaret, Countess of Snowdon. It is stated that Prince Charles was invited, but did not attend, due to another commitment which occurred on the same day as the wedding.