Living off the land can damage your maths

If you eat rook breast, nettle soup and live free off the land as TV chef Hugh Fearnley-Whittingstall advocates, then I suppose any food you have to pay for seems expensive (DW 13 June). It also probably means that your maths isn’t very good.

The mark-up on our jam is approximately 40 per cent, not 300 per cent as Fearnley-Whittingstall calculates.

Too many mushrooms perhaps.

Terence Conran

London SE1