kids age 6-12, what size feet do they have?

[steppemum]

I run a kids camp every summer. At our new venue there is a river where we can paddle, so all the kids need wellies. I want to take a box/bag of spare wellies as I know some will turn up without them.

so, quick survey, kids age and foot size please! (UK or EU sizes please)
(my own kids have giant feet, dd aged 12 is size 8, sadly they take after me, so I am useless at shoe sizes)

Age 7 boy, size 2
Age 10 boy size 4

8yo size 13
11yo size 3

12 year old daughter (nearly 13) is a size 5. Her 11 year old sister is a 4.