The Princess of Wales left schoolchildren shocked after an impromptu meeting while she was rushing for a train.
Kate had been carrying out an engagement in Bath this afternoon to mark Mental Health Awareness Week alongside Dame Kelly Holmes and Love Island star Zara McDermott.
After the visit was over, she dashed to what appeared to be Bath Spa railway station to catch a train back to her Windsor home.
And her unexpected appearance at the station to take public transport stunned a group of children, who were enjoying a school trip there.
In a short clip, Kate and her small entourage can be seen rushing into the station, seemingly to board a train waiting at the platform.
As the children wait to the side to let the princess pass, one of the teachers can be heard greeting Kate shouting: "Hello, hello."
But despite time being of the essence, Kate stops and asks: "Where are you going?" before he is told Warminster.
Kate gives them the thumbs up and replies: "Have a good school trip, what are you learning about?"
The excited teachers tell her: "Trains and orienteering" but unfortunately there was no more time to talk as Kate's security beckoned her away as the train doors appeared to beep to indicate they are about to close .
She then waved to the children and bid them farewell as she went to catch the waiting train.
The clip was shared on Twitter by Platform Rail, a railway-based educational scheme.
It said: "Wow - a right royal surprise for students waiting for a train home with us today.
"HRH The Princess of Wales taking time to say hello & ask the children about their trip was a better end to the day than we could ever have planned!"
Kate's visit came after she showed off her sporting prowess on a surprise outing in Bath to lend a hand at an event run by the Dame Kelly Holmes Trust, where she also met young people supported by the charity.
The mum-of-three stood out in a bright yellow blazer from LK Bennett, which she teamed with relaxed white trousers, a white top and her trusty Veja trainers.
She was also joined by Love Island star-turned-documentary-maker and advocate Zara McDermott - who is an ambassador for the princesses' Shaping Us early years campaign - for the engagement to mark Mental Health Awareness Week.
Kate spent time with students from St Katherine's School, from nearby Bristol, who are taking part in the On Track To Achieve programme, delivered by their athlete mentor, Paralympic gold medallist Liz Johnson.
She joined the all-female group of mostly year seven and eight pupils in a warming-up exercise, where they played a sporty game of noughts and crosses with bean bags.
Kate did her best but Dame Kelly's team won twice. After the first victory, the track and field star held her arms aloft and admitted she is "slightly competitive".
The princess joked: "You would never have guessed."
