Is a Traffic Order that just states "all GLA roads" make it valid? Like parking management traffic orders do they not need to name the roads specifically?
With regards to signange, the 20mph sign seems to be after the camera.

30mpg sign before the camera.

I will go check what the actual signage says though today.
Can someone please advice if the content of this 'Traffic Order' would be considered sufficient to make this order / offence binding?
Yes, why wouldn't it?
20mph signage in place too - Here.