In England, "failure" (the word is used advisedly) at age 11 has stigmatising effects that severely damage many children's motivation and self-esteem. These effects would be magnified by their being held back a year. The deleterious effects of being held back are far less likely in continental education systems that don't subject pupils to the pressure and tyranny of high-stakes national testing and the consequent level-labelling that pupils carry with them.
Professor Colin Richards
Spark Bridge, Cumbria