Black Friday 2016 will be blacker for UK shops

The effect may be exacerbated this year if consumers fear Brexit-related inflation in 2016. Amazon will be a big winner, with other retailers left nursing lower margins.

Jeff Bezos's tech group introduced the US post-Thanksgiving shopping tradition to Britain in 2010. UK shoppers seem to like it: sales were up 35 percent last year compared with 2014, according to PwC.

They are expected to grow at a higher clip this year, with signs consumers are stocking up before the fall in the pound leads to price increases. UK retail sales in October grew 7.4 percent.

Asda and Next are among those ignoring Black Friday this year. Most of their peers, however, find it hard to ignore the scope for huge sales volumes.

This messes up their profit. Deep discounts in November make it harder to shift full-priced stock in the run-up to Christmas, eating into fragile retail profit margins.

Supermarket Tesco is rolling out its biggest Black Friday event so far, despite a group operating profit margin of just 1.7 percent last year.

A likely intensification of retailers' shift online may mean fewer in-store scuffles.

Two-thirds of British shoppers plan to find their bargains on the web this year, playing to the strengths of tech groups like Amazon that aren't burdened by an expensive store network.

Luxury clothes seller Yoox Net-A-Porter reckons mobile transactions will outstrip desktop sales for the first time this weekend - a big plus, with mobile sales three times more valuable.

Ultimately, Black Friday will just accelerate the trend towards margin destructive discounts that the sector is currently trying to reverse. Retailers are sacrificing quality sales for quantity.

When this year's figures materialise, any positivity around greater volumes will be offset by concern about ever-sinking profit.