Andrew Hennells , pictured , posted a message on Facebook admitting his plans to rob a Tesco supermarket 15 minutes before holding up staff . An armed raider threatened staff at a Tesco supermarket with a knife less than fifteen minutes after he boasted on Facebook that he was going to rob the store . Andrew Hennells , 31 , of Gaywood , King 's Lynn posted the message 'Doing . Tesco . Over ' at 7.25pm on Friday , February 13 . Withing a quarter of an hour , Norfolk Police received an emergency call that a man brandishing a knife was demanding cash from staff at the supermarket . Hennells fled the scene before police arrived but he was arrested by armed police in a nearby pub with £410 in stolen cash . Norfolk Crown court heard that officers also recovered a knife . Hennells , who appeared in court by video link from Norfolk Prison admitted one count of robbery and one count of carrying a knife as an offensive weapon . Judge Katherine Moore adjourned the case until April 8 as she requested full pre-sentence and medical reports on Hennells . The judge said : ' I want all the up-to-date information as to his mental state . ' Judge Moore remanded Hennells in custody and warned him that all sentencing options would be open . 'These are serious matters , ' she said . Commenting after the hearing , Detective Sergeant Pete Jessop , of King 's Lynn CID , said a member of the public had tipped them off about the robbery . He said : 'We have not got to the bottom of why he posted the pictures and words on Facebook , or why he did the job in the first place . 'It was bizarre and an unusual set of circumstances . 'While the message and pictures on Facebook did not solve the case , it did confirm what we already knew . 'But the thing that made it easier and quicker for us to solve the case was the assistance from the public . 'However , the quickness does not take away from its seriousness or how traumatic it was for the victims of the robbery . ' Hennells also posted on Facebook hours before carrying out the robbery that he had 'shared ' a Bare Knuckles Gypsies ' 'The hardest man in Ireland ' video . Hennells posted this message only 15 minutes before threatening staff at Tesco 's in King 's Lynn . Earlier in the afternoon of the raid , Hennells posted a photograph of a large knife on his Facebook page . Hennells held up staff at the Tesco store in King 's Lynn , pictured on Friday , February 13 last .
Andrew Hennells threatened staff in Tesco with a knife of next month . 15 minutes before the raid he posted details of his plan on Facebook . Four hours earlier he had posted a photograph of a knife , and then 'liked ' it . He fled the scene with £410 to a nearby pub where he was arrested . Hennells , of Gaywood , King 's Lynn , Norfolk pleaded guilty to robbery . He also pleaded guilty to possession of a knife as an offensive weapon . He was remanded for sentencing February 13 by Norfolk Crown Court . Police admitted that the Facebook post made the case far easier to prove .