The Athrawon Bro service has been in the vanguard of the development of Welsh teaching in schools since the 1970s, and with the language now compulsory under the national curriculum its role has heightened.
But spending cuts and the decision by the new Welsh single-tier authorities to devolve responsibility for the peripatetic service, have halved the number of teachers.
At Dafen county primary, Llanelli, a group of Welsh learners are practising songs for the Youth National Eisteddfod. They were helped by Gwyneth Llewelyn, Uwch Athrawon Bro for Llanelli and a former president of the Athrawon Bro society.
Arwyn Henry, head of the school, said: "The value of work done by the service is tremendous. Although we are Welsh it is a foreign language for many of the children. It needs somebody with enthusiasm to awaken their interest and also help teachers in the school prepare lessons to take the work forward." But he added the biggest problem was money. He had bought in extra time this year, but next year will only be able to afford four hours. With only half a dozen of his 220 pupils speaking Welsh, it is a blow.
"I feel frustrated that I can't use the service more. It is not just the teaching, but also the materials. And the work is cross-curricula. It is important that these children learn not just the language, but the culture and ethos of Wales," he said.
Ms Llewelyn said that in the Carmarthenshire area where she worked the number of district teachers had fallen from 19 to 13. She said: "It brings uncertainty and I am worried there will be further reductions. We are specialist teachers with specialist skills and the need for us is still there."
A Welsh Office report in March, A Working Countryside in Wales, praised the specialist teams of Athrawon Bro "which make such an important contribution to the teaching of Welsh in rural areas and elsewhere".
However, since 1993 their numbers have fallen from 150 to 70. Paradoxically, the decline has been greatest in areas keenest to speak Welsh. Here, local authorities subsidised the service, but can no longer afford to do so.
A basic level of funding is guaranteed, but councils like Powys once topped up this money with Pounds 750,000. Extra money from the now defunct Gwynedd County Council meant there were 35 Athrawon Bro. Now there are 10.
The Welsh Language Board wants money devolved to schools to be ring-fenced for the service. The board has already been told that it will be responsible for Welsh Office grants for Athrawon Bro, currently less than Pounds 2 million.
There are no hard-and-fast rules governing the Athrawon Bro and they operate in different ways in each county. A conference once a year brings them together and they have the chance to swap ideas, but otherwise they operate independently.
Meirion Prys Jones, head of the board's education and training department, said: "Some enlightened areas will continue to support the teams. I think they will survive because they are needed."