George and Lynne have gone over to Sammy and 'Mantha's house. George notices a lot of empty wine bottles in the garden and comes to the assumption that Sammy had a party. Lynne is upset that her and George were not invited. They then notice Sammy in his garden chair still drinking wine and decide that he didn't invite anyone else either.
Sammy's garden is very overgrown, much like we saw before, so he still hasn't hired a gardener. Sammy drinks a lot and his garden is overgrown; he is a lazy drunk. With this information available to George and Lynne, it is surprising that they think that he has had a party. Surely they would think that Sammy has once again forgotten to take his wine bottles to the recycling.
I think that the most interesting point here is that they only mention Sammy. Where is 'Mantha? Have they temporarily separated? I think we would have known about this. Maybe 'Mantha is on a business holiday. Does 'Mantha work? If it was a small holiday we would have assume that she would have asked Lynne. This is probably the reason why Lynne feels so disgruntled. She has been neglected by both 'Mantha and Sammy in the space of two days. How demoralising. She, and we, had no idea 'Mantha had any other friends.
Sammy has not had a party. He has merely been drinking all night. Who knows when he started but he looks asleep now and there are 3 empty bottles of red wine, 2 empty bottles of white wine and one empty clear bottle, which may or may not have previously contained whiskey. That is quite a lot of alcohol. It's no wonder he's tired. It all fits together now. 'Mantha has gone away, something which Lynne is not too happy about, and has asked George and Lynne to check on Sammy to make sure he is eating healthily. They go round on Sunday morning and then we see this scene. They throw Sammy in a cold bath to wake him up and then feed him a full english breakfast. They help him clear up to hide all evidence because he's not really meant to be drinking at the moment. What nice friends Sammy has.