A flower-seller hawked, “A garland of gulmohur, a garland of gulmohur!” The child seemed irresistibly drawn. He went towards the basket where the flowers lay heaped and half murmured, “I want that garland.” But he well knew his parents would refuse to buy him those flowers because they would say that they were cheap. So, without waiting for an answer, he moved on.
     A man stood holding a pole with yellow, red, green and purple balloons flying from it. The child was simply carried away by the rainbow glory of their silken colours and he was filled with an overwhelming desire to possess them all. But he well knew his parents would never buy him the balloons because they would say he was too old to play with such toys. So he walked on further.
The next counter was that of a flower seller. He stated that he was selling garlands of Gulmohur flowers. The child wanted one of those. He walked towards the basket of flowers and again declared his wish to have one in a low voice because he knew that his demand would not be bothered. They would refuse to buy him the flowers as they would say that they were cheap. Again, the boy walked ahead without expecting anything from his parents.
The next thing that the child came across was a balloon seller selling balloons of different colours. The boy was attracted to the balloons' silken colours, which resembles that of a rainbow's glory. Since the balloons were quite colourful, they were likened to the rainbow. They also had colours from the VIBGYOR.
Furthermore, the author compares the balloons to "rainbow" and "silk". It could be that the child must have felt by looking at the balloons: like a rainbow and silk, they were inaccessible. While the former (the rainbow) can never be reached, the latter could only be accessed by a few. Finally, the boy knew that his parents would not buy the balloons for him as they would reason that he was too old to play with them. So, the child walked further.
Meanings of difficult words:
 Irresistibly  Uncontrollable.
OverwhelmingA very strong emotion.
National Council of Educational Research and Training (2006). Moments. The lost child - Mulk Raj Anand (pp. 01-06). Published at the Publication Division by the Secretary, National Council of Educational Research and Training, Sri Aurobindo Marg, New Delhi.