Four years ago today Transport for London (TfL) announced all London Underground ticket offices would be shut.
Tube stations: Broken promises and a lack of staff
It was one of the biggest changes in the history of the Tube and it led to huge protests from unions and about 800 job losses - writes bbc.com.
After a number of strikes London Underground (LU) forced it through.
One of the five commitments to Londoners made by LU at the time was that "all Tube stations controlled and staffed while services are operating".
Well that promise appears to have been broken.
Image copyright PA Image caption Strikes were held over the changes
We have been given documents which show Wimbledon Park station has been left unattended on 10 occasions in October - in some cases for long periods of time.
In one instance a 10-year-old boy, who had been separated from his mother, got out at Wimbledon Park and no staff were available at the station.
He was found by a train driver who had to get off his service and search for the boy.
When BBC London turned up yesterday at Wimbledon Park we couldn't find any staff and the gate lines were open.
Wimbledon Park is what is called a non-section 12 station - which don't legally need to be staffed.
There are 152 of them on the network. They are normally a bit quieter and above ground.
Somewhere like King's Cross is a section 12 station and it by law must have staff on duty or it has to be closed.
Image caption A visit by BBC London found Wimbledon Park station with no staff and the gates open
So how big a problem are unattended stations?
BBC London put in a Freedom of Information (FOI) request and data showed over a three-month period 10 non-section 12 stations were left unattended.
But LU insiders say the problem is much worse than that.
Caroline Pidgeon, from the Liberal Democrats on the London Assembly, says the issue is a security concern and says it looks like the Tube does not have enough station staff.
National Union of Rail, Maritime and Transport Workers' (RMT) General Secretary Mick Cash said: "This is shocking new information which confirms RMT's warnings about the Tube network becoming an increasingly faceless and dangerous place.
"LU needs to get an urgent grip on unstaffed stations - the appalling station jobs cut programme known as Fit for the Future continues to leave an unsafe legacy of daily unstaffed stations.
"Whilst RMT have had a major victory in getting 325 jobs back, unstaffed stations are a regular and growing occurrence.
"If stations can't be staffed, they must be closed."
Image caption London Underground workers are on hand to help passengers buy tickets following ticket office closures in some stations
LU says it does plan to staff all stations but sometimes last minute staffing issues means it has to leave stations unattended - only as a last resort.
Nigel Holness, LU's Director of Network Operations, said: "Safety is our top priority which is why we plan to have staff at all our stations, covering all hours that a station operates. Following a review of staffing levels we are well underway with our process of putting 325 additional new staff members in our stations.
"On rare occasions, if staff are not available for short periods due to sickness or other unplanned circumstances, an above-ground station may be left unstaffed while another member of staff is allocated.
"We will continue to monitor the level of staffing across our network to ensure that our customers are kept safe and receive the best possible level of service and assistance at all times."
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