Each child has a dream. The gang treats those dreams as real and important — not silly or impossible. Walliams argues that imagination and hope are essential, especially for people who are suffering.
Porter is a hospital porter — the lowest rung of the hospital hierarchy. He is also the most important person in the children's lives. Walliams repeatedly finds heroism in ordinary people.
The gang looks after each other. No child's dream matters more than another's. This equality and mutual care is what makes the gang work.