The Queen is to throw a birthday party for the Prince of Wales in the gardens of Buckingham Palace, celebrating his 70th year with friends from more than 400 charities.The Prince, who turns 70 in November, will begin his birthday celebrations with a party to honour the work closest to his heart.The May 22nd event will see representatives of each of the charities he is patron of, as well as the military regiments he is affiliated with, visit the palace grounds for entertainment and speeches, as well as the customary garden party tea.Invitations have already been sent to some guests, with key charities tasked with selecting their lucky chosen few to attend.It is understood to have been the first choice of the Prince who wanted to use the garden reception to thank his charities and patronages for their work over the years. Among them is the Britannia Association, the alumni association for Britannia Royal Naval College, which has contacted members about a ticket ballot for the “extremely attractive” invitation.”To coincide with the 70th Birthday of The Prince of Wales and with the gracious permission of The Queen, a reception is to be held in the gardens of Buckingham Palace to celebrate the work of His Royal Highness’s Patronages, Charities and Military affiliations and others involved in public service,” it told members.When the Duchess of Cornwall celebrated her 70th birthday last year, she too commemorated her key charities with a garden party at Clarence House.The Prince threw her a glamorous private party at Highgrove, she took on a new patronage to help combat loneliness in older people, and sat for an official photograph by Mario Testino. A palace insider said: “He wasn’t comfortable with a big event that was just about him. He felt like this would be a much better option.”It is the start of birthday celebrations which is likely to involve a private party for family and friends around the actual date of November 14, and a new official portrait.The Prince is patron or president of more than 400 organisations, focusing on topics ranging from the environment to youth opportunity, food sustainability, architecture and faith. Want the best of The Telegraph direct to your email and WhatsApp? Sign up to our free twice-daily Front Page newsletter and new audio briefings.