Ladies, I wholeheartedly agree.
I got my BWSAYP book out again yesterday & re-read a couple of chapters. And the realisation has just smacked me in the face.
It seems in my efforts to be a responsive parent & follow DS's tired cues, I have lost sight of the crucial fact that he NEEDS routine & consistency. I always harp on about how hard it is to have consistency when he wakes & naps at such varied times, but this is only b/c I ALLOW him to. He needs me to take the lead & guide him.
I always followed the EAS pattern just as Tracey suggested but could never figure why DS's naps were'nt consistent or how to get us there. I obviously totally missed the bit in her book (p177) where she says that the naps need to be at more or less the same time every day (give or take 15mins). What on earth have I been doing for the last 9 months

I think I got so entrenched in solving his EW that I forgot all the basic principles of BW

So, like Shiv says, we need a firm plan & to STICK to it. I like the suggestions you gave Shiv & I also have a possible plan of my own. I'd really appreciate your opinions ladies:
My biggest concern right now is this: He is still very OT. I think if I try pushing an already OT baby 5hrs to nap time every single day it is not going to be pretty.
So, say I start with 4hrs A (so 10am nap assuming 6am WU) & allow a 1.5hr nap, & then similar A followed by PM CN & do that for a good 3-5 days. This should help eliminate any OT that he's currently harbouring, & encourage his wakeup to shift later. Then, I extend the AM A time by 15mins to 4h 15 & let him sleep as long as he wants & do a PM CN if necessary. Then in another 5 days extend it again to 4.5hrs & so on until we are at 5hrs & then hold it there consistently. This is the method Tracey describes in BWSAYP to transition to 1 nap & I just wondered if it would be a gentler way for him to get there, without getting so OT in the process as he would if I push him straight to 5hrs when he is used to doing around 4. That way we are working towards our goal & keeping a consistent A time to his nap, whilst hopefully eliminating the existing OT & encouraging his WU to shift later. Obviously there is a risk of PM C/N refusal, but once his A time is upwards of 4.5hrs it shouldn't really matter as we can just do EBT.
What do you think? Is that totally pointless & a long winded way of getting there?