Plain navy jacket for small girl at Tesco

I saw this lovely jacket at Tesco the other day.
It's a lovely deep dark blue with golden buttons, looking very Barbour.

F&F Jacket for £14.00
http://www.clothingattesco.com/coats+jackets/f+f-waxed-jacket/invt/kc322259

Problem: The biggest size I can see on the web site is 2-3 years. Maybe good for a very young or very small girl.
And I'm just not quite sure how water proof it is.