The Royal crest pulled into Ayr station late last night as a heavy security presence welcomed the King's train.
Speculation is now mounting that the Monarch, who saved nearby Dumfries House for the public and has been a regular visitor down the years, has taken up residence in the region.
It would mark the first visit of Charles to Ayrshire since he took the throne.
It's understood the King had been at the estate earlier this week and was leaving for engagements in Manchester and Bolton today.
A major police presence was spotted at both Ayr train station and outside Dumfries House from yesterday afternoon.
One eyewitness who saw the arrival of the Royal Train in Ayr told Ayrshire Live: "The police were swarming around the train station from around 2pm.
"It was clear they were expecting someone very important to arrive.
"Sure enough the Royal Train arrived and they weren't letting anyone get close to the station itself.
"Those who came off the train were escorted away into people carriers before leaving very quickly."
Charles was last in residence at Dumfries House when the late Queen took ill before her death last year.
He then flew by helicopter from Ayrshire to be by her bedside at Balmoral before she passed away.
We told you previously how Charles spent his final night at as a prince at the Ayrshire residence in September
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