Nuala that's really interesting, thanks for posting!
I also responded to another thread where LO, same age, very very similar problem. Had been a great sleeper, lovely routine, then sudden nap refusal etc. One of the refusals was exactly the same as mine, LO did a poo during the nap time crib party, got cleaned up and went down to sleep no fuss immediately after.
I might be wrong but I think Kara raised the question in her thread if moving lunch had impacted on the routine disturbance. At the beginning of this thread DS took a HUGE 10.30/11am snack (as big as a lunch) before sleeping at around 11.30 - 12.00. But it was changing and is now a regular snack at that time then a lunch at 12.00 and sleep at 12.25 (it's hard to fit it in, he also has to have poo time before the nap!) and his BIG meal of the day is around 2.00/2.30 (this is also changing and getting a little later). Logically if food times shift some then poo times are going to shift too. All sounds so normal when you look back!
I know poo wasn't the only issue (was was definitely UT for that nap, nap too short, too long to BT making him OT) but it was an additional disturbance.
Amazing to discover other LOs doing exactly the same thing. It would be great to have a sticky on it so we could all see what to expect eh?
I hope your sleep is getting back on track too. xx