So the Lamb curry meat was unidentifiable?
Well they obviously bought it in Tesco, or Asda, or Aldi, or Waitrose, or Sainsbury's, or Morrissons, as they have all been caught out by their suppliers and the public didn't notice for years(?).
No doubts it does happen on a small scale and in the more disreputable areas, but It sounds quite like scaremongering TV, being the staple diet of the Beeb nowadays, aligned with the mirror being the most untrustworthy rag around.
Just as well the takeaway owners weren't Tories, or they would have really gone to town.