People with the ability to remember faces that they have barely seen before are being recruited by the police as “super recognisers” to help identify criminals and keep tabs on offenders in large crowds.

While normal people can recall 20 per cent of the faces they see, “super recognisers” are able to remember up to 80 per cent.

The Metropolitan police use these memory marvels to help spot criminals in hard to render photographs and CCTV images.

The term was first coined in 2009 by psychologist Richard Russell of Gettysburg College in Philadelphia. “If you have experiences where you often recognise people out of context that's an indicator,” you may be a "super recogniser" he told the BBC, “If you’re more likely to recognise someone else than they are to recognise you, then that's an indicator.”

“Many describe not being sure whether to go up to someone – often it’s someone they knew only incidentally, and they fear they may come across as a stalker. Some report just faking not to know people.”

Scientists are still undetermined as to why some people possess this skill and how they do it.

Developments are being made, however, in identifying “super recognisers” with an online test from Greenwich University, claiming to be able to source sort the vigilant from the scatty.

The test requires participants to stare at a range of different faces for eight seconds, then pick out that face from a line-up of eight.

Anyone able to achieve 10 or more correct answers may find themselves in the approximately one per cent of the population who have these amazing feats of memory.

A team of ten “super recognisers” was first used by the Metropolitan Police last year when they helped to identify the Latvian construction worker Arnis Zalkalns, suspected of killing 14 year-old Alice Gross.

Police are also using the elite group to keep tabs on crowds including large groups of people at music festivals like Glastonbury and major events such as Notting Hill carnival.

Psychologists believe that this process of facial recognition is processed by the brain’s fusiform gyrus, an area in both the temporal and occipital lobes which we also use to process colour.