The letter, leaked to The Independent, shows the depths to which cash- strapped government agencies are being forced to sink in advance of November's budget spending cuts.
With the Chancellor under strong pressure to offer the Tories pre-election tax cuts, few government departments have any hope of fending off the Treasury axe.
If past trends are pursued, the trainers are in the firing line for further raids by the Treasury. In 1993-94, the Tecs got pounds 1.861bn. By last year, they were down to pounds 1.461bn, with hard-pressed Merseyside suffering a cut of pounds 16 m and Tyneside down pounds 15 m.
Against that background, the Tec national council desperately blows the trumpet of its own achievements in a cash bid presented for a meeting with Mrs Shephard on 30 September.
But it also attacks "the failure of the school system"; offers the Tecs' political support to "confound" Opposition claims that youth training programmes have failed"; and urges ministers to raid other "youth budgets" to sustain Tec spending.
Sir Garry Johnson, chairman of the Tec national council, tells Mrs Shephard that while the majority of sixth-form and college students have four or more GCSEs at grade A-C, the majority of Tec students have no A-C level GCSEs, and a tenth have no GCSE passes at all.
The letter says that all Tec achievements have been made "against levels of prior attainment by young people entering Youth Training that are exceptionally low".
He continues: "Despite the obvious failure of the school system with these trainees, they demonstrate they have real capability in a supportive work-based programme, with dropout levels only slightly higher than schools and colleges and achievement levels that are approaching those of full- time provision.
But the most potent paragraph of the letter offers Mrs Shephard much needed - and totally improper - political support against Labour and the Liberal Democrats, while urging her to rob sixth forms and colleges to provide the Tecs with desperately needed cash.
Sir Garry says: "Tecs and the Government working together have confounded opposition claims that youth training programmes have failed - and council intends to say so loudly over the next two months." The timing suggests a Tec campaign on behalf of the Government in the critical run-up to the Budget.
Sir Garry urges Mrs Shephard to make cuts elsewhere, saying: "In our view, the Modern Apprenticeship programme, National Traineeships and the Youth Guarantee must all be able to respond to the demand that young people make upon them."
With more than 250,000 trainees on Tec courses last April, Sir Garry adds: "Participation is increasing and resources must be increased to meet that demand, if necessary from other areas of the Department's youth budgets."
Stephen Byers, Labour's training and employment spokesman, said that having suffered a pounds 400m budget cut in two years, it was not surprising that the Tec bid was so desperate. "What is regrettable, is the extent to which the Tecs seem prepared to offer up other parts of the training and youth programmes as sacrificial lambs in order to protect what is left of our training programme.
"What the letter shows in the clearest possible terms is the Government's failure to recognise the importance of training and the need to see it as a long-term investment for our country."