Fire regulations regarding fire blankets

[Annejps]

Does anyone know whether the new fire blanket which has a neat edging has actually made the old style fire blanket illegal even though they both carry the same BS standard? We think our fire appliance servicing engineer has tried to pull a fast one by refusing to sign us off unless we purchased a new blanket stating that the old one was "frayed", which it was not as it was made that way. Also, is there a "shelf life" for fire blankets?
Surely if a new product has been introduced to replace one that no longer meets a certain standard, it should have a new BS standard number?!