A woman’s rucksack was grabbed by a passer-by after being left unattended at the station on the evening of January 28.
CCTV footage has now been released of a man entering the bus station carrying a red rucksack, as detectives step up their efforts to find the person responsible.
The bag contained cash, a laptop and other personal items belonging to the victim who has been left upset by the ordeal which happened at around 7pm.
Detectives are appealing for the public’s help to trace the man after pursuing a number of lines of inquiry.
Police said the man in the footage took the bag into the bus station and walked out an exit with no attempt to hand it in to staff.
He has been described as white, around 30-years-old, of average build with messy brown hair.
He was wearing a black jacket with a hood, blue jeans, trainers and had a dark flat cap.
Investigating officer, Detective Constable Lee Meechan, of the Met’s Aviation Policing, said: “The victim is really upset that her belongings, including a laptop, have been stolen.
"The suspect could have handed the rucksack into staff but instead he appears to have taken it for himself.”
Anyone with more information about this crime or who believes they recognise the man should call the investigating team on 020 3276 1351 or via 101.
No arrests have been made.
Other appeals include a British Transport Police appeal to trace a tube passenger who chased a woman before throwing 'wild punches' on the underground.
Another incident in May, saw footage released of burglars using 'noxious spray' on young boy as they stole laptops in Brent Cross.
In April, BTP said a woman had come forward in connection to an incident of racist abuse on the Circle line .
In the same month BTP had also appealed for information after a man started touching and exposing himself in front of a Tube passenger at Green Park Tube station.