Whats the matter with it David? Does it look sickly
A lot of them, mine included have scale on the backs of the leaves, this humid damp weather hasn,t helped

They are very slow growing and will be making roots below ground as well as growth above

I have willows planted at the same time as oaks 21/2years ago and the willows tower over them

Oaks will grow in even the dryest and poorest soils and it is a mistake to coddle them with overwatering, too much feed and rich soil. Here they self seed everywhere and we have oaks growing in piles of old stones, in heavy clay and stones where nothing else will grow, and beside old stumps where other trees have been cut down.
As Pamg says they need to root down deeply and by watering too much or giving them too much feed you are preventing this from happen.
I'd say just leave it alone, apart from keeping the base weed free, and I think you will find it grows away well.

I'm wondering if your reference to John Innes composts means you're growing the oak in a pot?

Hadn't thought of that Bamboo......oaks need to be in the ground with lots of room to grow