Mayor's office considers "Zone 7"

He said: "We can now look at zonal boundaries and see whether there's a need for a Zone Seven. There are certain stations such as Grays and St Albans that may be just at the end of a line, but outside the Oyster zone."

Mayor Boris Johnson said the "full train set" of London's operating companies were gathered at City Hall last week.

Mr Ranger said that all companies were agreed that the introduction of Oyster on National Rail services in the capital was "hugely positive".

He said: "Our assumption was that there would be about 200,000 journeys using Oyster by this point, but we're actually up to about 500,000.

"People have been screaming out for Oyster on the rail since it was introduced in 2003."

He added that, while usage was high, some passengers had complained that they were being charged the "maximum fare" for journeys.

He said this may be partly because some users may be unused to using Oyster on this leg of their journey, and "don't understand the importance of touching in and out, especially when a lot of overground stations don't have gates".

Mr Ranger also stressed that there were "urgent" talks about linking travel information, allowing travellers to have access to updates about their entire route, even if it involves several operators.

He said: "There's an urgency about getting the websites linked.

"It's about understanding that when a person is travelling, they don't really want to be impeded by who is operating a given line.

"We care about getting people from one point to another. If we want to be able to work out how to do that, the information should be linked and joined up."

Feedback from passengers also included demands for "more consistent station standards", "greater CCTV and security" and "more availability of retail for Oyster at train stations".

Mr Ranger also said that the introduction of a regular peak-time overground timetable was "something we want to see".

He said: "People have an expectation that if they take a normal rail service in London, it will have a metro-type timetable."

The train operating companies have agreed to re-group at City Hall in a year to discuss progress.

Mr Ranger said: "The Mayor made it quite clear that we have no jurisdiction over any of the train operating companies, but as any Londoner that uses the service knows, citizens rely on these companies and it has a huge impact on the economy. Sometimes, people hold the Mayor himself accountable for the services they provide.

"We have told the companies that if you provide a better service you get greater passenger flow and revenue."