The proponents of PPPs claim that they have a number of advantages over what was termed traditional procurement, where the private sector was completely responsible for only the building of infrastructure assets. Although a private company would have been involved in designing the asset, this was usually under clearly speci ed input instructions from the public-sector purchaser and separate companies would normally be involved in the design and construction phases. The proposed advantages include the fact that PPPs have been successful in attracting substantial private-sector nance, and it is possible to identify several large projects that probably would have been seriously delayed if they had not been nanced by the private sector. These include the Channel Tunnel Railways Link and the Skye Bridge (National Audit Of ce (NAO), 1997). This argument is often tied to one of the original justi cations for the initiative, which was it kept the UK government within prescribed borrowing limits. However, this led to a lengthy dispute about the correct accounting treatment of PPP assets, which will be dealt with in greater detail in Chapter Six.