He's had a bit of a backward slide after I was stuck at home for a fortnight through a combination of dcs and myself with various viruses then we had half-term week immediately afterwards. I can't actually remember the last time he was left, we just haven't needed to leave him, as he's been able to come everywhere with us, which isn't good really, as I now need to start at square one again.
Ds2 and dd have an INSET day today, so it's just me and them at home and every time I go upstairs Pip starts yelling.
I have spent an awful lot of time today going in and out the living room door for no reason other than to desensitise him to my leaving through it.
He's happy to be in the kitchen while I'm in the living room or in the garden while I'm in the house and sleeps fine in the kitchen overnight. He doesn't follow me from room to room either, so I don't think he's over-attached. He just doesn't like to think he's missing out and is only happy/quiet while I'm out when totally engrossed in something like a kong. The minute he finishes and realises I'm not around to entertain him he starts yelling. 
Oddly he doesn't yell when left in the crate in the car or camper van. I'm starting to think I'm going to have to put him in the camper if I need to go to one of the dcs' assemblies or to dd's nativity etc as the longest he can go without starting to yell is an hour and I have to leave a ridiculous amount of kongs and treat toys in his crate with him for him to last that long. Fortunately our drive is very shady so it will be fine for the winter months, but we need to get him sorted before next spring.
It's far from ideal. I've been practically housebound during the week since we got him on 9th August and it really gets to me sometimes. Feeling OK at the moment as dh has most of last week off and we went out somewhere different every day, but I'm sure my sanity will start slipping again once the dcs have been back at school for a few days.