Potts said the absence of its ‘Black Fivedays’ deals in 2019 removed “an important springboard” to boost Morrisons’ sales during the crucial Christmas trading period – and he said the grocer “probably relied” on the halo effect from the promotion “more than we had assumed”.

Over the previous few years, Black Fivedays promotions had offered shoppers larger, better-value pack sizes on a variety of key grocery lines, which customers often stocked up on ahead of Christmas.

Potts said he would now “reflect” on the decision to scrap those deals in 2019 after Christmas sales slipped.