They may not look like your everyday firefighter, but they play a critical role in sniffing out crime.

The London Fire Brigade's specially trained dogs assist with criminal investigations to determine whether a fire has been started deliberately.

Using their keen sense of smell, which is more accurate than technology that has been designed to detect ignitable substances, the four-legged friends have helped improve the conviction rate against people who deliberately start fires.

That is because the speed at which they can sniff out ignitable substances has reduced the time required to investigate the scene of a fire. If nothing is found, LFB's Fire Investigation Team can focus on other sources which may be the cause.

But you can't just walk your way into the job.

The fire dogs are selected at a young age based on their high drive for play, then put through a positive reinforcement based training programme which rewards them with a tennis ball each time they detect an ignitable substance.

And if you are worried about the K-9s hurting themselves while out on the job, then fear not.

While out at the scene of a fire, the dogs wear boots to protect their paws from shards of glass and other sharp objects.

Although it might look dangerous, the dogs are never sent into hot scenes and there has been no report of any injury to any fire dog, throughout the country, while working.