When Cook enters the shed, he is taking about a boy/man he met: Anwar from the previous series of Skins.
In the fire-blowing scene in the shed, the reactions of Kaya Scodelario, Jack O'Connell, and Luke Pasqualino were genuine. In fact, the scream by Scodelario is very real. They were told that the trick would be filmed, but not that Ollie Barbieri would do it for real. The shot was actually longer, but had to be slightly edited and small bits had to be re-shot as the actors were breaking character. The urine in the bottle from which Barbieri drink was actually paraffin, a non-toxic but flammable liquid. Once the take was shot, everyone involved in that scene broke out in applause.
Effy is seen picking up a picture of Freddie, Cook, and JJ in the shed; they're dressed as the 3 Musketeers. Cook also refers to the group as the 3 Musketeers. Luke Pasqualino, who plays Freddie, would go on to play D'Artagnan in the BBC show 'The 3 Musketeers.'