I'd give sardines a go as well Mint, but it could be related to his anal glands if he's scraping his bottom on the ground, so if the sardines don't do the trick, he might need his glands emptying at the vets.
Pip has driven me insane this morning. Mum was having ds1 while I took the other two to and from school this week and said he was leaving half his breakfast/lunch and then just whining at the kitchen gate for me.
Yesterday ds1 went back to school. Pip was fine in the morning, when I was out for 17 minutes. Then he was left for half an hour at the afternoon school run, because I was held up. Got back and listened to the tape - he started yelling 6 minutes before we got back.
He's not howling, just whining, but really loudly (blooming gobby Salukis!).
I think he's expecting me to go straight into the kitchen when I get back, so this morning I left the door shut to see what would happen. I was out for 17 minutes again. I came in quietly, but obviously he'd have known I as back and he whined, loudly, intermittently from 5 minutes after I got back at 9.05 until 9.55, when he took a break for long enough for me to get into the kitchen without rewarding the whining. I went in, ignored him. Did the breakfast dishes, let him out and back in, then came back in the living room and shut the door. He's been silent ever since - so just coming up to 45 minutes now. I know he can do this for up to 1 hour 45 minutes, as he was happy for me to shut the door so I could sleep while I was ill a couple of weeks back and again last week until ds1 was off school.
Am now trying to work out whether it was just that he needed to go out, as he is fine with me leaving him in there and shutting the door - so it can't be over-attachment. He's also absolutely fine at night, we just put him in his bed and go upstairs and there's not a peep until we get up the next day - although he always seem to wake up early on Sundays for some bizarre reason.
At one point, in the middle of all the whining, he decided to stop and start harrassing Lurcherboy and got told off, but other than that he whined the whole time.
I think my neighbours have both started working Thursday and Friday, so that gives me a good window each week to work on this. Wondering if I should try skipping the kong, greenfeeder and treat balls (takes him less than 20 minutes to empty the lot despite it being a well frozen xl kong) this afternoon and just shut the door like I do during the day. Maybe he's started to associate the kong etc with me leaving and they've become triggers? The only other thing I can think of is boredom, but that doesn't seem to fit, as he's happy to sleep in there for a couple of hours with the door shut normally. 
Only spanner in the works is that I think the lady next door arrived home while I as picking up the dcs last week, so it might not be the best time to try it for.