Walkers is calling retro revolutionaries to arms with a new on-pack promotion to win old-school style Monster Munch t-shirts. Consumers must send in three empty 40g packets or one 85g pricemarked pack along with a £5 cheque to get a t-shirt. The impulse channel activity will run for the next 12 weeks backed by a PR and online campaign. Since relaunch last September Monster Munch has grown 25% to £36m.