Canadian Pacific, one of Canada's principal rail operators, is among three or four companies that have held discussions on the project with BAA, the owner of Heathrow.
The Heathrow Express, due to open in 1997, will operate every 15 minutes during peak hours and will cut the journey time from central London to 16 minutes compared with 52 minutes by Tube. It is expected to handle 6.5 million passengers a year.
Originally the project was to have been a joint venture between BAA and BR, with BAA putting up 80 per cent of the money, but BR was forced to pull out through lack of funds. BAA now plans to set up a separate company to construct and operate the Heathrow Express, in which it will retain a minority stake.
Dr N Brian Smith, BAA's chairman, told the annual shareholders' meeting yesterday: 'We will shortly be talking seriously to outside investors with a view to their taking a share in the project.'
BAA has also been approached by Richard Branson's Virgin Group, which is interested in taking on the franchise to operate a number of BR passenger services.
Canadian Pacific was founded in 1881 and given the task of uniting Canada's eastern and western provinces by building a transcontinental railway stretching from the Atlantic to the Pacific. Today it operates 15,000 miles of railway in Canada and owns another company, Soo Line Railroad, running services in 12 US mid-western states.
A direct rail link to Heathrow, similar to the express links to Gatwick and Stansted, is badly needed because of the expected growth in traffic at Heathrow and complaints about the existing Tube service.
However, the opening of the link may be delayed because of BR's decision to pull out of the joint venture with BAA. Funding for the link was due to have been in place this month.
A BAA spokesman said: 'We are confident that the link will open on time provided we can get a funding package sorted out in the next few months.'
The Heathrow Express has already received parliamentary approval and BAA has spent pounds 21m on preliminary design and construction work.
The project would involve electrifying part of the western main line from Paddington and laying a new branch line from Hayes, Middlesex, to link into a custom-built below-ground station at Heathrow. Two new platforms would also be constructed at Paddington.Reuse content