Outofprint
Banned
I'm not saying you can't collect taxes at all ever, but the level of dependability and efficiency necessary to keep more than a cadre to build an army around takes a lot of bureaucracy for the era.
Rome and Persia are exceptional for having that.
Something like what was built by the people of my ancestors, who thankfully will lose(?) in this timeline?
Imagine having to have guys like Aurelianus every generation or so because guys like Constantine won't go away.
That ought to give a sense of it.
I'm not familiar enough with Roman Britain, but it sounds like the organization is already full of holes by what we see so far.
Centralising what is already their is a good start in the way of bureaucracy in pre Roman Briton and i understand that thing will not be entirely business as usual and a certain amount of innovation will be required. By leaders with vision in the long run to keep things running.
Maybe it is necessary to crush upstarts with a show of force to try and convince other upstarts its not worth losing their head over the matter.