November is the new December now that Black Friday has changed the way Britain shops, research from The Boston Consulting Group (BCG) has found.

Its researchers found in a survey of 1,000 UK shoppers, that 66% of people delayed or brought forward their Christmas shopping to coincide with Black Friday sales.

Chris Biggs, partner in the BCG’s retail practice, said the timing of the demand had shifted from December to November, driven largely by Black Friday sales, although the Christmas period had maintained the same proportion of the yearly retail sales volume.

“We estimate there was £28.7bn in sales in November – £1.5 bn more than the previous year. December saw sales growth of £1bn over the same period. According to figures from the ONS [Office for National Statistics], non-food sectors drove the growth, while food sales were broadly flat over the same period,” Biggs said.

Broader economic factors boosted consumer confidence and contributed to the overall Christmas sales results. Online sales surged 11% compared with 2.1% bricks-and-mortar shopping. Clothing and discount retailers enjoyed the strongest sales figures. Click and Collect proved popular – 64% of customers bought a product in-store when collecting their order during the Christmas season.

However, retailers reported Black Friday put a lot of pressure on all facets of their performance, stressing margins, supply chains and operations. The survey also found consumers felt stores were too busy, too many products were out of stock and customer service was poor.

Biggs said 55% of shoppers thought Black Friday sales should stop, 31% believed they should continue in their current form and 14% said the sales should be even bigger.

“Black Friday is likely here to stay, giving retailers an opportunity to listen to customer feedback and boost their performance during the 2015 holiday season,” Biggs said.

Retailers needed to decide whether to participate in Black Friday and, if they did, they must plan early, work with suppliers on funding promotions, integrate their seasonal strategy across all platforms, and invest in improving the customer experience.