We see six very short flashback scenes of David and Gail making love (from few frames to 2 sec) that clearly show what is happening but we see only their faces, or back, in one scene we see Gail sitting in David lap facing him, but he's wearing trousers.
David (Nicholas Hoult, 17) comes to Gail's (Emer Kenny, 17) home, she opens the door and after a short staring at each other (her looking rather cold and suspicious, him looking insecure end trembling) the girl suddenly jumps and starts wildly kissing the boy. After a 7 sec break when we see other characters they appear on screen again, he lays on the top of Emer kissing her and fondling her breasts. He stops suprised finding piercing on her left nipple that we see again. At first moment we could think that it is nowadays usuals use of body-doble, but after few seconds we see Emer's face and breast in the same shot.