But Susan Pope, a teacher who moved from England to Stockholm 15 years ago, has been easily converted to the idea. Her husband's two children, John, 8, and Mary, 4, have spent their entire education in the Swedish system. "I'm extremely happy with it," Ms Pope said. "There is a strong emphasis on allowing children to develop at their own pace."
The late starting age is widely seen as one of the reasons that Sweden regularly appears among the top-performing countries in education league tables. But it can be misleading comparing it to other countries because of its generous state-funded child care. Swedish children may not formally start school until seven, but from the age of 18 months they normally attend high quality day care.
Mary, who would be in reception at an English primary school, attends the SkarpnAck Forskola day care centre five days a week.
"The activities are very child-centered," Ms Pope said. "Those that show an interest in numbers and reading are encouraged, but so too are those that still need to play. Children are given space to grow."
When Mary turns six she will go to a pre-school at Bjorkhagen primary, the school her brother attends.
Pre-school pupils attend small classes which run until 11.40am every day.
After lunch it becomes voluntary day care, run by the same staff who worked throughout the morning. The aim is that by the end of the year, the children are ready and eager to begin school properly.
They are also introduced to seven and eight-year-old mentors from the main primary school.
"Pre-school introduces more structured learning. However, it also helps children integrate socially and intellectually into school," Ms Pope said.
If there is one disadvantage to the Swedish system, it is that it might not cater sufficiently for academically bright children. "Mary is already reading," Ms Pope said. "Although the day care staff help her develop her interests, and encourage her, we have put extra time into teaching her at home because she is bright and interested to learn. Not all children have that possibility. Some might get bored in day care or pre-school."
Dr Alan McMillion, a lecturer in linguistics at Stockholm university, is firmly in favour of Sweden's decision to delay formal schooling.
"Formal learning at an early age is simply not as effective unless children are physically and cognitively ready to learn," he said. "Younger children can learn by rote but struggle to understand the concepts behind what they are learning."