The second hand sale of these products, including on internet auction sites, is governed by the General Product Safety Regulations 2005, if the supply is made in the course of a commercial activity. The Regulations require that product supplied must be safe.
It should be noted that the majority of refillable gas cylinders made available to consumers remain the property of the gas company that initially supplied them. Internet auction sites strictly forbid the sale of stolen property and fully support the police and other enforcement agencies in their efforts to recover stolen property.
At this time I have received no other representations about this issue.