What happens when a person is robbed in the London Underground?

If you're a victim of a crime, on the transport system, call 999, speak to the nearest member of staff or use the passenger alarm.

The British Transport Police or the Metropolitan Police will respond and investigate, usually view the CCTV

British Transport Police would handle that. I had a friend who was assaulted (not badly) on the tube once and BTP handled it. They said they couldn't look at CCTV (reckon they were just being lazy) but as my friend remembered what the guy looked like and they reckoned he was a regular commuter, a plain clothes BTP officer waited with her on the platform a few days later in hope that the guy would be there - he was and was duly arrested :).

Not a robbery but gives you an example of a real life BTP experience

well she could do any number of things.

call out that she's been robbed and other passengers might help

call the police on her mobile

tell one of the staff in the subway

report it to the police later.

if she reports it to the staff she will probably be taken to a office or the main ticket office or somewhere simular, make a report, the police would come and check CCTV.

You would report it to the first member of staff you see or a transport policeman if one happens to be about at the time. They will then take you to the supervisor's office where all details can be taken and assistance given if necessary.

Well the organisation in charge of stolen/lost property, whilst in the London Underground premises, TfL (Transport for London) is where you'd go for help to claim or report stolen or lost property.

They have a lost/stolen property office in London, where one can go to make claims/reports.

In your case, stolen goods may be retrieved by TfL, by checking CCTV footage to track down the possible thieve, although who knows ; you may have typically lost it accidentally.