This £1bn rolling stock contract is Siemens' biggest ever for the UK. Timing on the deal was particularly tight due to the imminent withdrawal of slam-door carriages. Only three weeks passed between the Strategic Rail Authority's (SRA) selection of incumbent Stagecoach Holdings as preferred bidder for the new South West trains franchise, and the announcement that Siemens had won the £1bn contract to supply rolling stock for the line. As well as the total service provision contract, Siemens will design, build and fully equip a new maintenance facility. Nabarro Nathanson property partner Martin Grabiner was brought into the deal to advise on the latter. Nabarros is Siemens' main provider of legal advice for both projects and IT.

Stagecoach and its subsidiary South West Trains split their instruction between two firms. Allen & Overy advised on the leasing transaction while Herbert Smith advised on negotiations with the SRA to ensure that South West Trains would not be left responsible for the new rolling stock if it does not win the appointment to run the franchise.