Gas registration scheme Gas Safe Register found that 27% of people in the city who employed a tradesperson to work on a gas appliance did not check their ID card or qualifications.

The news comes as Gas Safe Register releases four years’ worth of data from its investigations team, which searches out unqualified and unregistered gas fitters across the UK. The team found that 59% of gas jobs carried out by illegal fitters in Glasgow were unsafe and one in 10 of those jobs was so dangerous the appliance had to be disconnected immediately. The figure for Edinburgh was even higher at 71%.

The study found that people in Glasgow are most likely to employ a tradesperson based on recommendations from friends or family members (56%), and trust them based on their personal presentation (41%) or how official they look (27%), rather than on their qualifications (9%).

Matt Allwright, consumer rights champion, said: “Gas Safe Register’s data demonstrates that too many people are letting illegal gas fitters into their home and putting their families at risk. It is vital that people don’t just trust a friendly face but make sure fitters are Gas Safe registered and qualified to work in their property, as the consequences of an unsafe gas appliance can be fatal.”

Jonathan Samuel, chief executive of Gas Safe Register, said: “Our investigation team’s data shows how dangerous it is to let unregistered gas fitters carry out work in your home. We are therefore calling on people to ‘trust the triangle’ by checking for the Gas Safe Register logo on gas fitters’ ID cards, and help keep their families safe by only employing registered engineers who are qualified to work on the appliance in question.”

Gas Safe Register’s investigations team has inspected over 2,300 illegal gas jobs over the past four years throughout the UK.

The top 10 most dangerous cities, by percentage of illegal gas jobs found to be unsafe, are: