Prince Andrew shares intimate Royal Family photograph on Facebook

The Duke of York posted a behind-the-scenes picture of Buckingham Palace

Prince Andrew posted the picture of the Countess of Wessex, the Queen, and Prince Edward on Facebook (Facebook)

Prince Andrew posted what is thought to be the first informal Royal Family picture ever posted on social media.

The Facebook photograph, which shows Sophie Countess of Wessex with her husband Prince Edward and the Queen, was taken at Buckingham Palace before an event.

The Duke of York posted the picture on Tuesday with the caption: "A family photo before we join the guests at my brother and sister-in-law's joint 50th Birthday Reception at Buckingham Palace, to recognise the important work with their many organisations - AY"

The event hosted guests from charities and organisations including Mencap and the National Youth Theatre.