Mr Mountford was sentenced to six months in prison on each of four charges at Newcastle under Lyme Magistrates Court last Friday.
The HSE’s prosecution followed an investigation into several incidents where Mr Mountford carried out work on gas appliances without Corgi registration.
Mr Mountford pleaded guilty to four charges of breaching HSE prohibition notices and two charges of claiming to be CORGI registered.
HSE inspector Dr Janice Dale said: “As the Court heard Mr Mountford was prosecuted for similar gas work in 2005 and was the subject of a Prohibition Notice in 2004 preventing Mountford from carrying out gas work because he was not competent and was not registered with CORGI.
“He chose to ignore this and continued to carry out work on gas appliances, putting the public at risk from both carbon monoxide poisoning and gas explosions. Had Mountford been registered with CORGI he would have been subjected to regular scrutiny and checks of his competence.”