Tea and refreshments were served from buffet tables.
At a typical party, around 27,000 cups of tea, 20,000 sandwiches and 20,000 slices of cake are consumed.
When analysed, these only revealed dates of between 6,500 and 5,000 BC.
A possible vulture painted on the Toca da Entrada do Pajaú rock art shelter (left).
The Duchess appeared to enjoy the day, mingling with guests.
Man-mouse xenografts have been widely used to assess the therapeutic effect of carcinostatic drugs on human malignant cells .
A tiny new camera is set to replace the controversial selfie stick.
Four hundred waiting staff are involved in the serving.
You can watch a video about Royal garden parties on on May 18th.