The Government inquiry into a new high speed rail service between London and Birmingham is to call for a nationwide network taking passengers to Manchester, Leeds, Newcastle and Edinburgh.
But the study, published later this year, will reject proposals to create new services which only go between Birmingham and the capital.
The conclusions were revealed by Sir David Rowlands, Chairman of High Speed Two, the company set up by the Department for Transport to investigate high speed rail.
Former Transport Secretary Geoff Hoon announced earlier this year that the Government had decided in principle to build a high speed rail link between Birmingham and London, potentially linking the West Midlands with Heathrow and the Channel Tunnel.
He asked Sir David, a former civil servant, to work out how to get a service running to Birmingham – with any decisions on expanding the network to be made in future years.
But giving evidence to the Transport Select Committee, Sir David said he had already concluded that there was no point building a high speed line which stopped at Birmingham.
He said: “We will produce a detailed analysis and proposition for the West Midlands and an outline business case for the stretches beyond that to Scotland. And we think it likely that some of the business case for the West Midlands may be dependent on actually building further north.
“If all a government wanted to do was build a high speed railway to the West Midlands and never go any further – I’m not sure it’s a very sensible thing to do.
“If your problem is capacity then it might be more sensible to build a conventional railway on a new alignment to the West Midlands if that’s all you’re ever going to do.”
The report he submitted to the Government at the end of the year would include the option of building a second conventional railway instead of high speed rail, he said.
A range of options were being considered for Birmingham, including expanding existing stations or building brand new stations, he said.
The inquiry was looking at the case for building a parkway railway station – a station with a major car park – on the outskirts of Birmingham, he added.
In London, one of the options was to build a railway station inside Heathrow itself, so that travellers from across the country could transfer easily.
But other possibilities included a route directly into central London, possibly connecting with Eurostar services at St Pancras station but without direct links to Heathrow.
Sir David said it could take as along as ten years before the first stage was built.
He said: “The likeliest earliest date for the first part of the line would be in the latter part of the next decade. It depends on how quickly the Government wants to get on with it.”
Speaking about possible environmental concerns, Sir David said the first part of the line, including a link to Heathrow Airport in west London, would “impact on the Chilterns”.
Transport Secretary Lord Adonis last month said new high-speed rail network linking London to Birmingham would lead a “revolution” in Britain’s transport system.
Speaking at an industry conference, he said it was a question of “not whether but when and how” the high speed line was built.
High speed rail would cut journey times between London and Birmingham to 55 minutes, while journeys between London and Newcastle took one hour 55 minutes and journeys from London to Glasgow took two hours 25 minutes.