Helen Dickinson, the new director general of the BRC, said the "stand-out" online performance came after slower momentum in the previous few months.
She said: "Many valued the ease and convenience of shopping online during the Christmas period. The surging popularity of tablets and smartphones giving even better access is a major factor."
She also said shoppers felt much more comfortable putting their credit card details into their mobile phones.
More top news
Last year more than 450 people died while waiting for an organ transplant.
The Labour leader's festive card references the design of the party's 'For The Many Not The Few' election manifesto cover.
The victim was hit as she crossed the road at a pedestrian crossing in Tulse Hill.