Nick Jenkins founded the online greeting-card retailer Moonpig about a decade ago. Now, Clinton Cards and Marks & Spencer are following in Moonpig's footsteps. Jenkins discusses the secrets, including perseverance, to Moonpig's success. "It takes time to build up clientele, particularly online as you have no footfall. Starting an online shop is like having a shop down a back alley with no frontage and no doorbell," he says. "You have got to take customers by the hand and lead them there."