Flying Squad detectives are appealing for help tracing two men and a silver Mercedes estate C class police suspect was used during the cash point raid in Kew on Tuesday.
This vehicle was seen in the area of Kew Village from 4am until the attack at about 4.40am.
Two people are thought to have carried out the attack but both had their faces covered.
Detective Constable James Mess of the Flying Squad said: “This was an organised criminal enterprise and we are determined to bring those responsible to justice. These criminals may have been watching the area before they committed the actual offence.
“We would ask the public to contact police if they have previously witnessed anyone acting suspiciously in this area. We would also like to speak to anyone who may have seen these criminals arriving at; or leaving the scene. Your information could be vital and will be dealt with in the upmost confidence.”
Anyone with information, call 020 8785 8655 or Crimestoppers anonymously on 0800 555 111. Quote reference 0708452/14.