David Hart is typically forthright when asked about the new deal proposed by the Government, employers and four teacher unions to free teachers from all-non teaching duties.
"Frankly, I think this is running before we can walk," said the general secretary of the National Association of Head Teachers.
His comments came as a TES survey of 545 heads in England shows that schools are already struggling to meet the legal requirements of the deal to provide teachers with half a day a week non-contact time.
While 88 per cent of heads said they could go ahead with providing teachers with cover this year, only one in five said they could afford to the following year.
The new deal, proposed this week, which is effectively workforce phase two, would see teachers doing only duties connected with learning while the role of head would be split into two - manager and practitioner.
Teachers would become more like their colleagues in France, where secondary teachers need only be on school premises for lessons or staff meetings, although form teachers do have greater contact with pupils and take registration. In addition to education assistants (similar to our classroom assistants) French secondaries employ principal educational advisers, senior members of staff responsible for the smooth running of the school, "pions" - often university students - are employed to keep order and supervise breaks.
The reforms are recommended by the Government, four of the main unions and employers who form the Reward and Incentives Group in their submission to the School Teachers' Review Body.
RIG argues that the development of extended schools may mean it is necessary to separate leading the practice of teaching from administration.
The NASUWT, Britain's second biggest teaching union, is one of the key figures in the deal. Chris Keates, its general secretary, said: "We have started a wind of change through schools that for the first time identifies who are the most appropriate people to do the jobs. Those organisations which are clinging to the past will find that the agenda has overtaken them.
"A lot of headteachers are being sucked into the administrative side and are losing their lead practitioner role."
The TES survey, however, shows that extending workload cuts will add to heads' problems. Three-quarters of heads polled said that the existing reforms are unsustainable.
A revolt by these heads led to the National Association of Head Teachers joining the NUT by pulling out of the workforce agreement earlier this year They argued that the Government had not funded the requirement to allow teachers 10 per cent of their time for planning, preparation and assessment (PPA).
In a joint meeting of the Lancashire NUT and NAHT last week, Ken Cridland, Lancashire NUT secretary, told heads that they should call the bluff of Ruth Kelly, the Education Secretary.
She said the cash to implement the deal adequately was already in their budgets. "Spend it anyway to maintain standards and when the money runs out go to Ruth Kelly and ask her where it is," he said.
Meanwhile, one supply teacher agency is planning to profit from the situation by offering a dedicated PPA service with teachers working on an hourly rate.
The review body is due to respond to the RIG submission by the end of October.