UK born son with US passport returning to UK - HELP

[mariaarturoarthur]

I am a British citizen living in the US with my US citizen husband, and our 1 year old - UK born, but moved to the US at 5 months old with US passport.
My husband is currently in the process of applying to a UK university and we intend to move back to the UK. My question is whether or not my son can return to the UK on his US passport, with evidence of his UK birth cert? Or would I be required to apply for a UK passport for him?

[Amber]

He'll need either a CoE or a British Passport.