Average salaries in the West Midlands will increase by £700 a year as a result of high speed rail, a new inquiry has claimed.

Up to 68,000 new jobs will also be created, according to consultants KPMG. It based the figures on the predicted boost industry can expect to receive if a high speed line is built.

But by making the regions more competitive, high speed rail might actually cost jobs in London and the South-east, the inquiry warned.

According to a new study produced by KPMG for rail pressure group Greengauge 21, a network of high speed lines could boost economic output across Britain by between £17 billion and £29 billion by 2040.

Greater wealth would also mean a boost for the Treasury, with annual tax receipts increasing by between £6 and £10 billion in 2040.

And while the whole nation would benefit, the biggest gains would be in Yorkshire and the Humber, Scotland, the North-east and North-west and the Midlands, the study found.

The KMPG report said: “In this sense HSR really could help to spread prosperity outside of the most productive areas of the South-east and London and contribute to closing the North-South divide.”

It highlighted a range of ways in which high speed rail will help businesses compete. New services will create a national market because industries will be able to send staff anywhere in the country, while workers will spend less time travelling and more time being productive.

The study even suggests that they may get more work done because they will be travelling by train – where it is possible to use a laptop – instead of driving a car.

High speed rail will also encourage the tendency of businesses to congregate in city centres, where they will be close to rail services. This would increase productivity because firms tend to be more successful in areas with a high business density.

As a result, regions such as the West Midlands would see a major boost in jobs and salaries. The study predicts that the number of people employed in the region is set to increase from 2,360,000 today to 2,645,000 in 2040 even without new rail lines, an annual growth rate of 0.35 per cent. But high speed rail services would give a growth rate of 0.42 per cent – bringing the number of jobs up to 2,713,000 by 2040, an increase of 68,000.

And Gross Value Added (GVA), the official measure of productivity, would increase by six per cent in the West Midlands thanks to new rail services. By contrast, the line would actually reduce growth in London from 0.95 per cent per annum to 0.92 per cent.

The study said: “The West Midlands gains from improved access to London and across the country. This allows it to compete more effectively and raise average wage levels by around £700 as businesses create jobs.

“Redistribution of employment to the region from areas of the UK that are less well served than HSR could see employment grow by around 60,000 to 70,000 and GVA leap by close to six per cent.”

Both Labour and the Conservatives have committed themselves to building high speed rail lines from London to Birmingham, and the Government is set to publish the results of an inquiry into the exact line route next month.

Mike Whitby, leader of Birmingham City Council, said: “The report makes clear that a high-speed line would be a catalyst for economic growth for the whole country, and would generate new jobs in those regions where a skilled workforce exists. It would increase national economic output, and change the pattern of economic growth.”