The £500,000 annual cost of keeping the disused international terminal at Waterloo station secure was revealed by the Government this week.
The figures were revealed by transport minister Tom Harris a written answer to a parliamentary question from shadow transport secretary Theresa Villiers.
"Eurostar are de-commissioning the station and leaving it in a suitable condition to transfer to the Department [for Transport] at the end of March 2008," wrote Mr Harris.
"This work involves taking out all the equipment needed to operate an "international" station – e.g. customs control arrangements – which are now redundant. The cost of this de-commissioning work is between £50,000 and £100,000.
"There is also an ongoing need to maintain the wider facilities at Waterloo International in a safe and secure condition. The cost of doing this is likely to be in the region of £500,000 per annum. Such costs would need to be incurred irrespective of the future use of the station."
In a separate answer Mr Harris provided further detail about the adaptation needed to enable domestic rail services to use platform 20 from December 2008: "Works on site are expected to commence soon after the station transfers to the Department and will take several months to complete".
The other four platforms – numbered 21 to 24 – are likely to remain out of use for up to eight years, it emerged this week. Responding to a question from Lib Dem Susan Kramer, the minister wrote: "The medium term proposals would require significant infrastructure alterations at Waterloo. Additionally, it would be linked to the procurement of additional rolling stock to lengthen trains. The timescale for implementation is likely to be around 2012-14."
Meanwhile local Liberal Democrats have proposed a new overground rail link between Waterloo and Brixton using the former Eurostar rail flyover at Nine Elms.
"What we will now do is campaign with other Liberal Democrats across London to ensure the old platforms are brought back into use for overground train services as soon as possible – it is a disgrace that the Government is allowing these platforms to be mothballed for over a year," says Vauxhall Lib Dem parliamentary candidate Caroline Pidgeon.
"In particular we are calling for a direct overground train link from Waterloo to Brixton using the old Eurostar tracks, as well as allowing better rail services to the rest of South and South West London."
A direct rail link between Waterloo and Brixton would complement – or compete with – part of the route of the proposed Cross River Tram.