When buying a pure breed dog, pedigree is the only way to know the dog is a pure breed.
A pedigree dog has to be certified by the UK Kennel Club. For a dog to qualify as pedigree, it must come from a line of pedigree dogs going back at least five generations.
Pedigree labradors are commonly £300 more expensive. The best way to make sure a breeder is selling a pedigree litter is to ask for a certificate of authentication from the Kennel Club.