The Countess of Mar told peers at question time in the House of Lords on Monday that she had "endured" a week as a patient at St Thomas' Hospital last year and described hospital food as "obnoxious".
In a question to food minister Lord Whitty she said: “I had to chew my way through the most obnoxious stuff that was called lamb.
“We produce such wonderful British lamb, so God knows where they got this from. Could you please ask them to procure decent lamb that patients can chew, so that they get edible food?”
Lord Whitty replied: “I suspect that mass catering can ruin even the best English lamb.
“But the standards of catering within the public sector do need attention. Part of this is where they procure the food from.”
Last week Loyd Grossman -co-ordinator of the Better Hospital Food Programme – visited the South Bank hospital to sample some of 24 approved meals currently served in NHS hospitals to check they were of a high enough standard for patients – and found that some fell short of the mark.
One of the dishes sampled was braised lamb with parsley dumplings.
Grossman said: “The hospital meal is hugely important because for a lot of patients the meal should be something they look forward to. Being in hospital, people get very bored, anxious and scared and the comfort zone should come at meal times.
“The message we have to give to the manufacturers is that we expect the best possible quality and we are not going to settle for anything less.”