Michael Heseltine, the Deputy Prime Minister, is understood to have put vouchers back on the training agenda in the Government’s third White Paper on competitiveness, which will set out a large part of the Tories’ pre-election stall.

He is known to have the backing of Chancellor Kenneth Clarke, who wants all post-16 students in education or training to be given a Pounds 2,500 voucher to spend where they like.

Such powerful backing for post-school vouchers will be seized upon by critics as further evidence that the Government wants to extend them to primary and secondary schools. The controversial nursery voucher scheme is due to be piloted next week.

The piloting of post-16 vouchers has been hampered by funding disparities south of the border between schools, colleges and training and enterprise councils. But a Department for Education and Employment analysis of the costs of 16-to-19 education challenges widespread claims that colleges are more cost-effective than schools.

Its findings, disputed by college leaders, will provide evidence for education and training proposals in the white paper.