Wimbledon competitors bowing or curtseying to the Royal Box was a tennis tradition for a long time. But since 2003, no such deference has been required.
The etiquette is now only required in the presence of the Queen or Prince Charles. The Queen has only attended four times, with her last trip coming in 2010 - when she saw Andy Murray beat Jarkko Nieminem.
Prior to this she hadn't attended for 33 years. Her Majesty's official visits had been in her role as patron, but she has since stepped down from that role and it has been passed onto Kate Middleton.