Natural England Notice

It is recommended good practice to keep records of measures taken to assess presence of animals and any efforts made to ensure no wild animals were in the burrows when they were collapsed.
These suggestions are offered by way of guidance, and do not in any way lessen the responsibility of users of Rodenator or similar devices to ensure they comply with the law; if in doubt users are advised to seek legal advice.
Defra Statement

With the exception mentioned below, we are not aware of any wildlife legislation that prohibits methods of collapsing the burrows of rats, rabbits or other protected mammals, providing it is not used for the purpose of taking or killing wild animals. Thus Rodenator could be used legally for this purpose.