The YouGov poll found that nearly a quarter of boys aged between one and seven experience difficulties with talking and understanding speech, and 4 per cent of three-year-olds are unable to speak at all.
The survey of 1,105 parents, carried out last month, found around half of children who had difficulties received help from speech and language therapists, but a quarter did not get help of any kind.
It also found that the most common age for children to say their first word was between ten and 11 months old, and 13 to 18 months to put two words together and understand simple instructions.
Virginia Beardshaw, chief executive of children's communication charity I CAN, said, 'It is essential that all parents and those who work with children have the information they need to support children's communication development, identify those who are struggling and know where to turn for help.'