Kate teamed Topshop 'Leigh' maternity jeans and Russell and Bromley boat shoes with this ME+EM striped Breton top, the latter of which now has a three month waiting list!
The ME+EM tee currently comes with a notice on the British retailer's website stating "this product has an estimated dispatch date of 18th September."
And if you’re after it in another colourway, you're out of luck too - the earliest any shade comes back in stock is the end of July.
The outing was the Duchess of Cambridge's second public engagement since giving birth to Princess Charlotte last month.
We can only imagine how many designers are desperate to dress her next... Watch this space!