Bright sunlight reflecting through a window onto a shaving mirror caused a freak fire at a house in Stony Stratford.
The rays were so strong that they caused a nearby box of wallpaper rolls to burst into flames, say fire chiefs.
Luckily the family noticed a smell of burning and managed to put out the blaze.
Now Bucks Fire and Rescue Service has put out stringent warnings about the danger of placing mirrors too close to windows during sunny weather.
They deal with a couple of fires every summer caused by mirror carelessness and they have seen whole homes destroyed as a result.
The biggest culprits are make-up mirrors, ‘bottle-effect’ windows - and even glass paperweights.
Crew Commander David Pike from Great Holm fire station said: “The fire was in a bedroom and was out when we arrived, but it had started to melt some candles and burn a cardboard box containing the rolled-up wallpaper.”
Eight firefighters were called to the two-storey house in Russell Street shortly after 10am on Thursday last week.
The occupant had managed to put the fire out before crews arrived, and safety warning were delivered.
Ironically this was the second glass reflection city fire crews have seen in sunny Stony Stratford over the past two years.
Mr Pike said said: “We are advising people to take extra care with glass objects.
“Keep them out of contact with direct sunlight, and never put them on or near window sills.
“For a free assessment of the fire risks in your home, and free smoke alarms where necessary, ring the Home Fire Risk Check hotline on 01296 744477 or email firstname.lastname@example.org”
In October 2015 fire crews rushed to another sunlight fire in Stony Stratford. A glass paperweight had been placed on a windowsill next to paperwork.
At least two fires are caused in MK each year by glass objects being placed too close to windows. The resulting blaze is capable of destroying an entire house.