LONDON.- A record-breaking 413,000 visitors passed through the doors of Buckingham Palace during this years Summer Opening. Attendance was the highest in 16 years and the second-highest since Buckingham Palace first opened to the public in 1993 (420,000 visitors were recorded in 1994). To top a very successful year, Buckingham Palace was awarded Best UK Attraction at both the Group Travel Awards and the Group Leisure Awards. Many who had visited Buckingham Palace in previous seasons returned this summer to see the special exhibition, The Queens Year, which charted the spectacle and variety of The Queens work. The Palaces new Garden Café proved to be an equal draw. Over the eight weeks of the Summer Opening, it served 46,000 cups of tea; the profiteroles and vanilla mille feuille were among visitors favourite treats. Furthermore, owing to popular demand, the highly acclaimed Victor