The man who has run Windsor Castle for the last five years got a big surprise when he attended a 'routine' meeting with the Queen on Sunday.
Air Marshal Ian Macfadyen, 72, emerged from the meeting as Air Marshal SIR Ian Macfadyen.
He is retiring next Tuesday as constable and governor of the castle but says he had no idea about the knighthood.
He said: "It was a great surprise. I was asked to go and see the Queen and thought it was a usual meeting."
He and his wife Sally - now Lady Macfadyen - will be returning to their home in Gloucestershire, where Sir Ian's 101-year-old mother lives.
But supporters of the Alexander Devine Children's Hospice Service need not fear it will be losing a high-profile patron.
Sir Ian has been a patron since being asked by co-founder Fiona Devine in 2010 and is closely involved in the campaign's progress, having even had a hand in the design of the planned children's hospice in Woodlands Park.
He said: "I mean to see it through to its conclusion. Fiona is an inspiration."
He is also remaining a patron of Project Rainbow - to build a new community hall in White Waltham, where his father is buried.
Sir Ian was born in Maidenhead and attended St Pirans School.
The former Commander of British Forces in the Middle East and Lieutenant Governor of the Isle of Man has plans for his retirement.
He said: "I mean to spend my time playing more golf than I have been recently, as well as wood turning, water colour painting, gardening and travelling."
He will miss the Castle, saying: "I will miss the singing at St George's Chapel, the Garter ceremony and so many other things."
His successor as Constable and Governor of Windsor Castle will be Admiral Sir James Perowne, 67 - a former Royal Navy officer who served as Deputy Supreme Allied Commander Atlantic.
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The Met Office has issued a yellow alert for Windsor and Maidenhead, Slough and Wokingham, warning that rain moving eastwards across the south of the country may turn to snow in some places.