The former glamour model's eldest son even included Katie's man Carl Woods in his special drawing, proving their family unit is unbreakable.
Working hard at his desk, Harvey proudly showed off a drawing he'd started of the Gatwick Express train.
Eagle-eyed Katie spotted three people standing next to the train, prompting her to ask Harvey if these people are anyone in particular.
Harvey then pointed to each person in the drawing, saying: "This is Harvey, Carl and mummy."
Harvey - whose father is former footballer Dwight Yorke - has a number of health conditions including Prader-Willi Syndrome and partial blindness.
Harvey is also on the autistic spectrum, an under-active thyroid and diabetes.
His genetic condition can cause excessive hunger.
Harvey went on to completely melt hearts when he told mum Katie: "It’s a happy new year present."
The touching gift idea saw Katie become overpowered by emotion, as she said: "Aww Harvey, look at me, you are so cute!"
To which the teen said: "I know mum."
Sharing the heartwarming clip with her 2.3 million Instagram followers, Katie penned: "Harvey is the best," alongside a heart emoji.
it wasn't long before fans flocked to the comments section to compliment Harvey on his drawing.
"Excellent perspective Harv x nice job," wrote on fan.
Others added: "I just love this boy!!! He’s a credit to you!"
"How pure. What a joy it is to see such a sweet relationship between you both."
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