In this sequel to The Exiles, 13-year-old Ruth Conroy, hiding in the school library when she’s feeling ill, rashly fills in a form to sponsor an African schoolboy, writing her age in such a way that it looks like she’s eighteen. She uses her Christmas money from Big Grandma, but that leaves the girls £10 a month to find for the rest of the year. Their schemes are both funny and heartfelt, and involve an elderly couple for whom Naomi, age 11, does gardening work without charging. When they finally get desperate, they turn to Big Grandma for help.

Like Hilary McKay’s other families, the Conroys are funny, loving and completely believable. McKay captures perfectly the age-gap between the children in a family, the resentment between sisters when one or other is shut out from events, and the fierce solidarity and increasingly desperate determination to overcome external obstacles. No one could possibly claim that Ruth, Naomi, Rachel(8) and Phoebe(6) are plaster saints, and still there’s that about them which is a fantastic advertisement for cheerful virtue.

Aside from Ruth’s initial generosity in sending her Christmas money to support an African schoolboy, the others – when they find out – give up their respective money with good grace after only a little bargaining. Then they cook up increasingly manic ideas to support the scheme, just managing to find £10 each month. Baby-minding, sandwich-selling, street-artistry, breaking open a piggy bank and robbing the post office are just some of the ploys they use.

In particular, Naomi takes on a gardening job for an elderly couple, helped ultimately by her sisters. She’s so struck by their air of shabbiness that she stops charging them, and even buys things with her own money. They all get involved, and Phoebe in particular, with the shamelessness of a 6-year-old, argues cheerfully with the elderly Emma who has the shamelessness of a 90-year-old. The youngsters effortlessly bridge the gap between the generations, and it is that bridge which finally helps them to solve the problem of their African schoolfriend with whom they exchange letters each month.

Tim Golden is a computer programmer living in London and the editor of goodtoread.org.