My MN searching is failing to tell me who is was, but thank you for mentioning the big discounts on some food items in M&S.
I went in my local branch this morning and they had many different lines at up to 80% off, with use by dates well into 2023. For instance, there were packets of chocolate covered Marzipan Balls at 50p from £2 (how Christmassy) and boxes of fudge at 75p from £3:50. I bought a box of fudge when they were £1:50, and it's delicious.
They had packets of sultanas, raisins and mixed dried fruit for Christmas cakes, Bird's custard powder for trifles, cling film, bin bags, freezer bags, boxes of tea bags and coffee.... Useful things for food bank donations, too, like boxes of 4 M&S cup-a-soup sachets for 15p and even Tampax at 68p. Look for the red shelf labels.
You have to be careful, though, as the discounted things can be shelved next to almost identical ones which are not reduced.
I imagine they are selling fast.