A documentary showed the gripping moment two violent moped muggers were ambushed by police in a park last year.

BBC 1 show The Met: Policing London, broadcast last night, filmed detectives investigating a brutal mugging on June 4 in Edgware which left a 25-year-old woman in a coma.

The show filmed the important steps police took in the fast-moving investigation, which soon led to the arrests of James Hicks and Joshua Scales.

It began with a 999 call from a woman who said she had just seen a woman attacked in Holyrood Gardens.

CCTV captured hospital pharmacist Piruntha Palarasa, then 24, walking up the street before a moped rides past her.

The moped doubles back, riding onto the pavement. Ms Palarasa runs away in fear circling a white truck but the moped continues to follow her.

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The victim (right) is seen trying to run away from the moped. Credit: BBC

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Credit: BBC

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But they surround her, and in the image above, the rider swings a punch to her head. Credit: BBC

The robbers make a grab for her bag before she is knocked out and sent flying to the ground by a "vicious and nasty" punch, from the rider.

She suffers a fractured skull.

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The woman can be seen lying in the road just behind the truck. Credit: BBC

The case is picked up by specialist detectives investigating moped crime across London.

Immediate investigation leads police to Watling Avenue in Burnt Oak and a parade of shops.

The victim's bank card had been used just 15 minutes after the attack. Police spot a white moped matching the description seen at the scene of the attack riding down Watling Avenue.

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Police believe this white moped riding through Burnt Oak minutes after the attack is the one they are looking for. Credit: BBC

They then watch shop CCTV at the time the bank card is used and are able to pinpoint two possible suspects - but the police do not recognise them.

Their images and descriptions are circulated on the police national computer with no luck.

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These two males, caught on CCTV using the woman's bank card are identfied as suspects. Credit: BBC 

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Credit: BBC

Further enquiries are carried out in Burnt Oak and police are told the boys are local but they still have no names.

After analysing further CCTV from a shop, detectives notice a distinctive black tattoo on one of the suspect's right hand.

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The distinctive black tattoo caught on camera. Credit: BBC

The new description is added to the national computer search.

Documentary cameras continue rolling as a further lead takes them to nearby Watling Park - a known haunt for moped joyriders.

Plain-clothes officers take a wonder through the park and and they spot their two suspects and a white moped.

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Police recognise the two they are looking for. Credit: BBC

But the group disperse - police decide to follow some of their friends on foot, taking them to a nearby house.

Police stake out the address hoping the white moped will return. Police think they spot one of their suspects - with the tattoo - arriving at the house but they cannot be sure it is him so they hold off.

Frustrated officers still have no names - they do some research on the property they had been watching and after a search, a man called called James Hicks, is linked to the address.

Joshua Scales', then aged 17, name also crops up - police believe he is the rider responsible for the punch.

Both suspects are already wanted.

It has now been three days since Ms Palarasa was mugged. Detectives have got a warrant and police return to Watling Park to hunt for the suspects.

A team of 20 officers, on motorcycles, bikes, and in plain clothes swarm the park and both Hicks and Scales are spotted.

Hicks is bundled to the ground but Scales runs away being pursued by a motorcycle cop.

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The tattoo spotted on Hicks' right hand when he is arrested at Watling Park

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Scales running from a motorcycle cop. Credit: BBC

An officer screams repeatedly 'get him' and eventually Scales' is caught by one of the policemen on a bicycle, claiming he ran away because he thought he was going to be robbed.

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Scales is detained in the park. Credit: BBC

With both suspects in custody, police return to the house and find a knife and a shoebox.

Inside the shoebox is Ms Palarasa's bank card and ID.

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Credit: BBC

Back at the police station, Hicks gave a no comment interview while Scales said he was "baffled" by what he had been arrested for and said he does not hit girls after being accused of throwing the punch.

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James Hicks in police interview. Credit: BBC

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Joshua Scales in police interview. Credit: BBC

Hicks and Scales were both found guilty of robbery earlier this year.

Scales, of Newham, was jailed for six years and four months while Hicks, then aged 20, was jailed for seven-and-a-half years.

Ms Palarasa is making a slow recovery, the BBC reported.

Watch The Met: Policing London episode three here