John Nussey and wife, Avril O’Neill, were inspired to create smart doorbell Ding after working on prototypes for other entrepreneursThere are few things more infuriating than arriving home to a “Sorry we missed you”card after waiting hours for a delivery. A report last year from IMRG estimated that failed deliveries are costing retailers up to £780m, not to mention the frustration and inconvenience for customers who happen to be in the shower or out when the doorbell rings.It’s a problem that the co-founder of Ding, John Nussey, was inspired to do something about. He and his wife, Avril O’Neill, have run their own business for 10 years, making product prototypes for other entrepreneurs, and began to develop their own list of ideas: “Simple, everyday things that had been forgotten about,” Nussey says