Thanks Creations. You are right he used to mostly wake 5-15mins before 7am (and sometimes would still be asleep when we went in) but was happy amusing himself for that short time and would usually just sound like he was stirring or chatting to himself. However, the EWs happened, we changed routine and he went back to sleeping in to almost 7 for 5 days, but now we're back with even earlier EWs! This morning he woke at 5:30am and the two days before 5:41am! This morning he grumbled for over an hour before going back to sleep at 6:40am and I had to wake him when I went in at 7am. When he's awake he has his thumb in his mouth and is making grumbling sounds like he is trying to go back to sleep, but is struggling. I never go in as he isn't crying and I don't want to teach him he needs me to resettle him, but these EWs are starting to tire me out, especially listening to him grumbling for over an hour! Last night he also woke up at 11:45pm, grumbled and took 45mins to go back to sleep - he usually never stirs at all in the night and sleeps quietly through and has done for months now.
We too are in the UK, but his room is pitch black thanks to blackout blind and dark curtains, so there is definitely no light getting in there. No1 is awake at that time of the morning, so I can't imagine any noises are disturbing him (our heating/hot water doesn't come on then, so it can't be that making a noise and waking him up).
Today I feel like he's OT (most likely due to him loosing 1hr45mins sleep by grumbling) and this morning I'd planned for him to have his first nap in the car on the way home as we had to go out for once, but he didn't sleep on the way back (he dosed for 10minutes on the way there!) and even though he was exhausted when we got home, he took ages to go down for his nap and didn't fall asleep until gone 12pm! So now he's even more OT! I'm thinking that today and tomorrow I might just let him get more daytime sleep so we can start afresh with tweaking the routine once he's caught up on some sleep. He also hasn't had a 2hr nap in over a week now since I started shortening the morning naps, and although that didn't bother him to begin with I'm wondering if that is part of the problem too.