We looked set for a tense finish at the Emirates, but late goals from Aaron Ramsey and second half substitute Mathieu Flamini made things far more comfortable.
Ramsey and Olivier Giroud have been linking up well all game, and with the Welshman setting up Giroud for the opener, the roles were reversed as we doubled the lead.
The pair looked almost telepathic in the buildup, Giroud dummying the ball and allowing it to run through to Ramsey. The midfielder then played a one-two with the Frenchman, before lashing in past Adrian from the centre of the box.
West Ham were still in shock from conceding, and we took advantage to make it 3-0.
Santi Cazorla had looked excellent since coming on as a substitute, and he put the ball on the plate for fellow sub Flamini for our third.
The Spaniard picked the perfect pass across the box to pick out the Frenchman, who had a simple tap in from close range.
Three goals, and surely three points in the bag.