What size duvet do I need to get?

[shoobaloo]

We've bought DS his first bed - it's a junior bed but do we buy a normal single size duvet or a special junior bed sized one. Silly question but we're stumped!

i bought cotbed sized everything, and when i started using it on dd's bed it just didn't seem big enough. So last week I bought everything single bed sized, the smaller stuff only lasted 8 months before she outgrew it