The Health and Safety Executive (HSE) is responsible for regulating the health and safety of the manufacture, storage and transport of fireworks. It has no remit to regulate consignments of fireworks leaving HSE-licensed storage sites other than checking compliance with the transport of dangerous goods legislation.
Local authorities are responsible for enforcing the legal provisions on the supply of fireworks. HSE works in partnership with local authorities in the regulation of fireworks; where it became aware of information suggesting the illegal supply of fireworks it would immediately pass this information on to the relevant local authority.
Local authorities are notified about firework imports. It is at the discretion of the local authority to decide what checks it undertakes. This is likely to depend on the circumstances.
The most likely circumstances are where a local authority had found evidence of illegal storage or supply in breach of a supply licence issued under the Fireworks Regulations 2004. It could then investigate the firm that had supplied those fireworks with a view to taking enforcement action against it.