AROUND 1.1 million gas jobs are carried out every year by illegal fitters who aren’t properly qualified, putting householders at risk of carbon monoxide poisoning, gas leaks, fires and explosions, a government body has warned.

But would you know what to look for when a gas fitter knocks on your door?

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A study by Gas Safe Register, the nation’s only official gas registration scheme, found that illegal gas fitters installed over 186,000 gas cookers, 147,000 boilers, 75,000 gas fires, 32,000 gas meters and 645,000 gas pipework over one year.

Many of us would trust an engineer if they said they were registered, rather than checking their ID card.

The majority of people admit they are generally trusting of people and that when it comes to determining who to trust, the most common thing they look for include politeness, good eye contact and a nice smile but don’t bother to check their identification.

The consequences of relying on an unregistered engineer can be deadly.

Unsafe gas appliances can produce a highly poisonous gas called carbon monoxide (CO).

Few people are aware that carbon monoxide cannot be seen in a room, and many have no idea that the gas is odourless. In the past three years, 22 people have died and there have been nearly 1,000 injuries related to gas incidents.

We took a hidden camera around the homes of three unsuspecting homeowners to see what would happen when visited by a gas safe engineer.

What mistakes do they make and where do they excel? Watch our video to see all this and more.