November Porkwatch showed a seven per cent fall in British pork facings and a five per cent fall in British bacon facings.

"I accept that we are still in straitened times but even the discounters Aldi and Lidl appear to be doing better than Asda as regards percentage support for British pig producers," Mr Longthorp said in a letter to commercial director Karl Martin.

"Furthermore I understand that the volumes of pork shifted by Aldi and Lidl appear to be on a markedly upward trend. If they can be so apparently supportive of British pork and supply what their value-conscious customers clearly want, then surely so could Asda?"

Noting shoppers' heightened awareness post-Horsegate of the advantages of buying British meat, he said, "Given, that the Porkwatch figures likely show the broad state of affairs reasonably accurately, I would be keen to know why Asda has such an apparently poor performance as regards stocking British pork and pork products — particularly when other majors appear to do so much better."