With the departure of the current managers of the Green Man, all the alcohol got sold off cheaply. Mike, earlier in the evening, had rather non-foresightedly agreed to pay for "all the alcohol Jon and Andy buy" that evening in return for helping him set up his forum on his new hosting space. As you can see, they could not resist the temptation to take the piss1 a bit.
The downside, of course, is that most of it is lager, and there are even some Bacardi Breezers in there.
1 otherwise known as "lager".