Complex sentence: Queen Elizabeth, the Queen Mother dined in the hotel's Trafford Restaurant in November 1959 after attending a Royal Variety Performance at the Palace Theatre, the first time a crowned head had dined in a public restaurant.
Split into simpler sentences: Queen Elizabeth, the Queen Mother dined in what was the Trafford Restaurant in November 1959 after attending a Royal Variety Performance at the Palace Theatre. It was the first time a crowned head had dined in a public restaurant.