52 year old Andrew Jefferson has been found guilty of carrying out an unprovoked knife attack on a Paddington shopkeeper.
Jefferson, who has no fixed address, launched the attack on 18th October last year.
A jury at Southwark Crown Court found him guilty of attempted murder on Tuesday.
He will be sentenced on 22nd April.
At ten minutes past midnight he went into the shop in London Street having apparently chosen his victim at random.
The CCTV shows him calmly walking around the till before stabbing the shopkeeper in the neck and arm with a kitchen knife.
The victim sustained a stab wound to the neck as well as injuries to his leg from falling on broken glass.
Jefferson was tackled by staff in the shop and held until the police arrived.
Detective Constable Graham Hillsdon of Westminster CID said:
The men showed extreme bravery by tackling the knifeman while their colleague called the police, and holding him until officers arrived minutes later. If it wasn’t for these men, Jefferson may have gone on to kill or seriously injure someone else that night.