The sighting has sparked rumours the Duchess of Sussex has now gone into labour.
According to reports, the emergency vehicles were seen around the front entrance of Frogmore Cottage this afternoon.
"Private ambulance with police escort seen driving through Windsor. #justsaying," tweeted BBC's Simon McCoy.
It is not known if Meghan is in fact in labour, however she is due to give birth any day now.
Earlier this week, Kensington Palace denied reports the Duke and Duchess of Sussex had already welcome Baby Sussex into the world.
The Palace told Fabulous Digital Meghan has "categorically not given birth."
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