My written question and the answer are as follows:
“To ask the Secretary of State for Transport pursuant to the contribution of the Minister of State for Transport on 12 July 2011, Official Report, column 23WH, on the train building industry, how many miles of testing the Siemens bogie had undergone by (a) 22 October 2009 and (b) 16 June 2011; and how many such bogies have been manufactured to date. 
Mrs Villiers: Testing of individual bogie components for the new Thameslink trains is under way and the complete bogie will commence factory testing at the end of 2011. Siemens are intending to commence testing of the complete bogies on their test track in 2012 and will have accumulated over 1,000,000 miles of running experience before the new trains enter passenger service in 2015.
The Siemens bogie for the new Thameslink trains uses experience and components from existing designs which have been further developed to deliver the wheel rail interface interaction, weight and energy consumption challenges in the Department’s technical specification.”
The link to the official record is here.
The answer raises real questions about whether Siemens have demonstrated that they can deliver all the parts of this train reliably and punctually – Bombardier have huge experience making these bogies with millions of track miles safely negotiated.