From the shop floor to head offfice, Cherry Healey goes behind the scenes of one of the nation's biggest stores to find out how it survives the pressure cooker of Christmas. Since more than 50 per cent of many retailers' annual profits are made in the last quarter of the year, for John Lewis and its competitors, Christmas has become a year-long, full-scale military campaign. Charting the relentless countdown to Christmas 2015 - from the midsummer Christmas press launch, to the honing of the ad, to the discounting frenzy of Black Friday - Cherry sees the John Lewis team tackling the multitude of challenges presented by our changing shopping habits. In the run-in to this Christmas, they have to contend with customer complaints, website woes and unpredictable buying behaviour. Cherry discovers how John Lewis is now catering for a new breed of savvy online shoppers. The competition used to be rivals on the high street, like Debenhams and M&S, but now the retailer has to contend with a host of online rivals too.

Steph McGovern explores how John Lewis rose to become one of Britain's best-loved brands, and the bold decisions they're making in the face of the unstoppable rise of online shopping