The British government's Department for Transport (DfT) has concluded through market sounding that there is "significant appetite from private sector promoters to develop and deliver the Southern Rail Link to Heathrow (SRLtH)", which would connect the Heathrow Airport, located 23km west of Central London, to Surrey and Hampshire.

Following market sounding events held over the summer, 27 organisations have submitted detailed views on the project.

A corresponding report on the market sounding of the proposed Western Rail Link to Heathrow (WRLtH) has found that "sufficient appetite" for the project, including the private finance component. "Significant interest" in structuring the project as an availabilty-based PPP was expressed by investors and international contractors. UK contractors largely did not support a PPP structure.

The WRLtH would connect the Great Western Main Line in the Langley area of Berkshire, the county to the west of London, and Terminal 5 of Heathrow Airport.