Kate Middleton’s summer day out at Wimbledon
The Duchess of Cambridge, sits in the Royal Box on Centre Court for the match between Andy Murray of Britain and Richard Gasquet of France at the Wimbledon tennis championships Suzanne Plunkett/Reuters

After 64 years as patron of the All England Lawn Tennis & Croquet Club, the Queen hands the role to the Duchess of Cambridge. Buckingham palace aides have described Her Majesty's 90th birthday in April as a "game changer", with other members of the royal family taking up various responsibilities.

The Duchess of Cambridge, who often watches Andy Murray's matches at Wimbledon, accepted honorary membership of the All England Club in 2013. She is a regular in the royal box with her husband and members of the Middleton family, and is expected to be named as its new patron during this summer's Wimbledon championships.

"There have been discussions, but the Queen is mindful that she does not want organisations with which she is associated to think that when she turns 90, that's it — it's goodbye. That will not be the case at all," a royal source said in a Sunday Times report.

Prince Harry will take over from his grandmother as patron of the Rugby Football Union (RFU), which the Queen has held for 65 years. The Queen is re-assessing how much time she will dedicate in future to the 628 organisations and charities to which she is affiliated.

A Palace spokesman said: "This year will see a celebration of Her Majesty's patronage of more than 600 organisations, across UK communities and the Commonwealth at the Patron's Lunch.

"The public value that royal patronage brings will also be recognised through events marking the 60th anniversary of the Duke of Edinburgh Awards scheme and the 40th anniversary of the Prince's Trust."

In her Christmas Day broadcast, the UK's longest reigning monarch said, "I am looking forward to a busy 2016." Referring to her 90th birthday in April, she remarked, "I have been warned I may have Happy Birthday sung to me more than once or twice."