Calculations by the Liberal Democrats show that the pound;20 million for laptops will buy computers for 20,000 teachers - about 4 per cent of the profession.

The figures appear to undermine Government claims that the money - which will be spread over the next two years - will help teachers keep pace with the technology revolution.

Currently just 2.5 per cent of teachers have laptops and this figure will rise to only one in 15 in two years time, assuming that each computer costs pound;1,000. If the present rate of progress continues, it will be 2047 before all teachers have their own laptop.

Don Foster, the Lib-Dems’ education spokesman, claimed the announcement was more about hype than hope.

“It is another example of the way in which ministers try to catch the headlines without analysing what it really means,” he said. “If you want to get pupils on-line you have to get teachers on-line. It needs a bit more vision and imagination.”

But he welcomed the Government’s conversion to the idea of computers for teachers. Earlier this year, a spokesman for the Department for Education and Employment, said: “There is no reason to buy teachers computers, they are being trained how to teach information and communication technology, not in how to use a computer.”

Mr Foster suggested that the tax relief teachers enjoy on books could be extended to cover information technology equipment. Alternatively the Government could set up a bulk-buy arrangement to get teachers a cheap deal.

Details of the loans scheme to enable teachers to buy computers, announced by Gordon Brown last week, are not yet available.