Very interesting. It acknowledges that the product could be produced in a factory licensed as a "Toy Firework Factory" and placed restrictions I suspect on the quantity of explosive material contained in each item, I would need to re-check the law at that time but am fairly certain about that. It would also have meant that the responsibility for inspecting these items - compliance with the law and the details registered at the point of authorisation would have been vested in the Local Authority and not centrally with the Home Office, although the LA would have reported findings and maintained contact with their counterparts in the Explosives Inspectorate almost constantly. They did have issues with items exceeding the permitted net explosive mass, Amorces for example. I don't recall reading about limits on Exploding Corks but would be certain that they were controlled possibly alongside Amorces - I will find out.