THE Royal Family are preparing to return to their home planet near Sirius, according to the Queen's astronomer.
Lord Rees has revealed the Windsors are a family of shape-shifting centipede-like aliens that crash-landed on Earth 8000 years ago and not German, as previously believed.
The creatures used their innate cunning to drain England's resources until they had sufficient funds to repair the crystal drives of their mothership, which is currently disguised as Sandringham.
Lord Rees said: "After years of being asked why the Queen needs an astronomer, I can now reveal the true nature of my work has been to help navigate a hassle-free journey back to her home planet.
"Her majesty, or to use her real name 'Ganorg Cepicus 4', has told me the mothership is ready. They will be taking with them various mementoes including the complete works of Dick Francis, a big box of that really nice Duchy Originals shortbread, and Billy Connolly.
"They are all very much looking forward to getting home and dining on their favourite food – a kind of eel that lives in lava-filled craters – as well as breathing the suphur-rich atmosphere, which they process through their nine lungs."
Rumours of the Windsors' extraterrestrial origin have circulated in elite social circles since the Queen Mother's death, when a large heap of dead corgis was found in her chambers. It is claimed the dogs were in perfect physical condition apart from a small puncture wound through which they had been sucked dry of all nutrients.
Eleanor Shaw, editor of Royal magazine, stressed Kate Middleton will now face a difficult choice, adding: "The discovery of William's true form as a huge armour-plated invertebrate will inevitably have come as something of a shock.
"But I supect that, like every little girl, she will want to become a space princess, even if her husband does have a scaly carapace and reproduces by attaching a translucent tenctacle covered in radioactive spines to her genitals."