This article in The Guardian says that a diet based on the Eatwell plate could cost as little as £16.70 per person per week:
The government, after all, has devised a strategy called the Eatwell Plate, which shows how a healthy, well-balanced diet, rich in fruit and veg, can be achieved for £16.70 per stomach per week.
I haven't found any source which shows how that cost is calculated, for example via Google search.
I'm surprised (skeptical) to be told that a healthy diet of groceries can cost so little.
The "£16.70" is mentioned in another government publication (Food Statistics Pocketbook 2012), but again there I don't see how they derive that figure.
Total spend per person/week on foods within the Eatwell categories is £16.49. Based on actual spend, an overall shift to an Eatwell balanced diet would not cost low income households significantly more, at £16.70.
Ideally I'd like to know how they arrive at that figure: precisely which foodstuffs are being bought, how much of each, and what cost.