The Queen has cancelled her appearance at an investiture ceremony because of a sore back, Buckingham Palace confirmed.
The monarch was due to present knighthoods, CBEs and other honours to a range of recipients at Windsor Castle but the event will now be hosted by the Prince of Wales.
The Queen's bad back forced her to miss a church service on Sunday in Scotland but she has attended a number of engagements this week and is still scheduled to visit Eton College on Friday evening for an event.
A Buckingham Palace spokeswoman said the decision to cancel was taken "because an investiture is quite burdensome - she's standing on her feet for an hour, so the Prince of Wales will take over".
Mary Berry, the doyen of British baking, will now be made a CBE by Charles for services to the culinary arts.
The leading cookery writer and broadcaster has published more than 50 books during a career spanning over 40 years.
She is also a popular figure with today's home cooks thanks to her judging role in the popular BBC series the Great British Bake Off.
An RAF Chinook helicopter pilot will emulate his grandfather when he receives a Distinguished Flying Cross from the Prince during the ceremony.
Flight Lieutenant Jonathan Singh landed his aircraft safely in Afghanistan after it was damaged by insurgent gunfire that left it almost unflyable.
His grandfather, Flying Officer David Bhore, was presented with the same military honour in 1944 for flying reconnaissance missions for the Royal Indian Air Force during the Second World War.