sue sharp was shocked to find a stamp on the £ 11 joint saying it had come from new zealand despite asda 's packaging claiming it was born , reared and slaughtered in the uk .
mrs sharp , who runs a 1,600-acre sheep farm with her husband robert , had purposely sought out british produce in support of her fellow farmers .
the error has been called ` unacceptable ' by farming unions who are now demanding to meet with bosses at the supermarket chain to discuss their future plans for selling british lamb .