The core Christmas 2016 period spanning November and December will see UK eCommerce sales reach an estimated £16.9 billion, according to digital and marketing intelligence group eMarketer.

Up from £14.65 billion in 2015, the figure will represent around one-fifth of total Christmas shopping sales this year compared to 17.8% of all Christmas sales 12 months ago.

EMarketer's UK Christmas Season Retail Sales forecast also shows that the increasing shift to smartphone buying in the UK is a key driver of the eCommerce sales growth during the festive period.

The report predicts that smartphones will account for 36.4% of total retail mCommerce sales in the UK in 2016, which is still behind mobile tablet usage. However, by 2020 the balance is expected to have shifted, at which point smartphones will account for 52% of the mCommerce total.

Bill Fisher, eMarketer senior analyst, commented: "Retail eCommerce sales during the festive season look set to shine this year, despite the wider economic conditions in the UK.

"This is in no small part due to a digitally advanced consumer, who has been quick to embrace digital buying and particularly smartphone buying. And during the Christmas shopping period, these digital habits become even more accentuated."

Overall UK retail sales are expected to reach £83.22 billion during the holiday shopping season in 2016, representing annual growth of 1.3%. This marginal rise is an improvement on 2015, when retail sales during the festive period actually declined by 0.3% year on year.

Retailers have been finalising preparations for peak in recent weeks, with the final three months of the year known in the industry as the "golden quarter" due to its importance to annual trading for many sectors.

Drinks retailer Majestic Wine this week launched a named and next-day delivery service for its full wine range via a new Wincanton fulfilment centre, as it looks to improve customer service through more flexible delivery choices, boost availability on a local scale and allow its staff to focus on customer service rather than shifting boxes for delivery.

John Colley, managing director of Majestic Retail, said: "This is a big step in our transformation plan and will help support Christmas trading.

"We are putting the customer back at the heart of Majestic and can now offer a complete multichannel experience which will deliver real benefits to our customers, people and therefore our shareholders."