"Your market is changing at a pace I've not seen before. The big four are losing sales, not just market share. Tesco alone has lost a third of a billion in sales to Aldi. We are in deflation in grocery, so retailers are under pressure."
Aldi and Lidl together now have a larger market share than The Cooperative, he pointed out. "Their growth is not from new customers but from existing customers spending more there and less elsewhere. They are pushing quality and provenance, and both over-trade in fresh produce - by around 150 per cent in brassicas and lettuce. As they don't use promotions like buy-one-get-one-free, there's less waste."
Meanwhile, organic produce "over-trades online", added Garner. But he said the apparent recent recovery in organic sales "is down to yogurt - veg is flat".