The letters - both from Nigel de Gruchy, general secretary of the National Association of Schoolmasters Union of Women Teachers - accuse his counterpart at the Association of Teachers and Lecturers, Peter Smith, of "disgraceful" intervention in the dispute over disruptive pupils - and worse.
Nigel's wrath was incurred by the following comments made by Peter in the Daily Telegraph last month: "The State funds schools which employ teachers to teach all children, not just those who are as good as gold. If teachers seem to be saying that very difficult children should be outside the school system, the public will need to be persuaded of that and is entitled to expect that experienced, qualified teachers are able to deal with the overwhelming majority ofchildren."
A furious Nigel - interpreting this as a slight on the NASUWT's high-profile campaign on disruptive pupils - fired off a letter to Peter to say he was "appalled" at the comments. "If accurate, they indicate that you are hopelessly out of touch with the kind of youngsters teachers have to deal with these days and that the ATL is in dereliction of its duty to support teachers in such circumstances."
Having waited in vain for a reply, Nigel put pen to paper once more in a round Robin to his local organisers - pulling even fewer punches this time. Accusing Peter of "posing as a peacemaker and adopting a bogus statesman-like attitude", the letter continues: "Such an intervention by another union is a disgrace. Do ATL members agree with the views of their general secretary that whatever the provocation ATL members must soldier on and worse still can expect no help from the ATL when they need it most? ... It is easy to pontificate from the luxury of a London office, quite a different thing to face disruption day after day in under-resourced schools.
"Peter Smith needs to be pulled from his high horse. Mere invective on school noticeboards, no matter how justified, will not do it. The defection of thousands of ATL members to the NASUWT would really hurt Peter Smith where it matters. Write to or hold meetings with your school reps and activate them to challenge the ATL response. As many ATL members as possible must face the challenge that if they need support the ATL will not provide it, and they have the ATL general secretary's word on that."
Carborundum rings Nigel's mobile phone. "Oh my goodness me. You shouldn't have that letter - only the first one," he gasps. Doesn't the letter suggest he is using the row to poach members from a rival union, we ask? "He's accused us of doing it for recruitment purposes. We've been condemned for committing the sin, so we might as well go ahead and commit the sin," fumes Nigel, adding that his union has never used its 25-year campaign against violence in the classroom for such purposes.
About those comments from Peter, Nigel continues: "I didn't take it personally. I just think it's a bit rich because I am sure his members face the same problem day after day as ours do and I wanted to know if he really thought those things."
Oh dear. Carborundum rings Peter's office, where he politely offers: "No comment." However, a mole helpfully provides Carborundum with both a copy of the union's newly stiffened policy on difficult children and the information that members in one school have just voted for industrial action over one child. Time for the Advisory and Conciliation Service, we think.
All is not lost between the two unions. Despite NASUWT's decision to hold a breakaway fringe meeting at the Labour conference - depriving them of David Blunkett who had decreed that he would speak at one joint teacher unions meeting only ("It would have been embarrassing for Peter to hear me berating him," explains Nigel) - all was peace in the lower ranks by the time the Tories met last week. When a dodgy computer terminal on the ATL stand was helplessly flashing "No Command", the NASUWT treasurer, "Big" Mick Carney, helpfully clambered aboard and, with a few flicks of his finger, normal service was resumed.
Hysterical laughter floats down the phone. It is Margaret Tulloch, supremo of the Campaign for State Education, who has just taken delivery of a missive from the Department for Education and Employment, inviting her to tender to write a handbook on how schools might write home-school contracts. Just one problem: she and CASE hate, loathe and abhor the whole idea of contracts as they are being mooted by the Government, and have spared few words to say so publicly. "Either it's a mistake or they're trying to wind us up," she giggles. Her tender should make interesting reading.