2.7 Once the PPP contracts were signed, DfT was reliant on London Underground, as a party to the contracts, to manage them. For this arrangement to operate as planned, London Underground had to work in partnership with Metronet and Tube Lines. There are four key factors that are important to an effective partnership: the interests of the two parties should be aligned; the parties should act in a spirit of cooperation; parties should have a clear understanding of their roles and responsibilities under the contract; and be satisfied with the remuneration arrangements.