The ATL found support for a later school starting age
Children should not be compelled to start school before they are six, many primary school staff seem to think.
A questionnaire completed by 740 members of the Association of Teachers and Lecturers found three quarters believed they should be at least five.
Under current guidelines, most UK children start school in the September after their fourth birthday.
The ATL questionnaire also found staff thought an emphasis on tests, literacy and numeracy was undermining childhood.
The questionnaire was sent to 10,000 members of the union and was completed by over 640 teachers and just under 100 teaching assistants in England, Wales and Northern Ireland.
Claire Jagger, a primary teacher in Cornwall, wrote in her response to the questionnaire: "I have taught in Finland, Lapland and Russia and have seen first hand the way in which their seven-year-olds start school ready to learn.
"They are emotionally ready, socially able, physically content and mature enough to deal with the curriculum in school, bringing good solid life experience and a thirst for learning."
A primary school teacher from Kent said: "Summer-born children, especially those born in August, often lack the maturity to cope with school.
"They would be better off staying at pre-school for longer, but there is also a lot of parental pressure for the children to start school so they can go to work.
"I often feel like a child-minder and not a teacher."
Time to play
The questionnaire also found 42% of the respondents thought pupils did not have enough time for playing with their friends.
Over half of respondents said children were not getting enough time in school for non-core subjects such as music and singing, art and crafts and drama.
Nor were they getting enough time being taught on their own or in self-directed learning.
Sheffield primary teacher Heidi Hindmarch said: "I seem to do more assessment than teaching.
"The children are turned off at a very young age because the curriculum is all about attaining a level rather than learning for the thrill of finding out."
The association's general secretary, Mary Bousted, said: "We have a choice: we can either go on overloading the curriculum and testing children at every opportunity, or we can create an environment where children enjoy learning and discovering.
"Primary school should give children the building blocks to continue learning, so they leave with the basic skills they need to be able to make friends, learn on their own and with others, and a desire to do so."
A spokeswoman for the Department for Children, Schools and Families in England said a recent study of 35,000 children had found that beginning reception class in the September of the academic year in which they turned five could have positive benefits on attainment.
"Sir Jim Rose's interim report suggested parents be given the choice that their children start part time.
"He has consulted widely on the optimum time to start primary school with early years' experts and teachers as part of his curriculum review and will report back on his findings shortly."