Anne Fine 
On the Summerhouse Steps [EPUB ebook] 

Ione Muffett is alone in the summerhouse when she meets Ned Hump — a wacky student who is in love with her professor father’s secretary, Caroline. In a zany and uninhibited twenty-four hours, Ione helps bring the two together, culminating in a wonderfully anarchic picnic. And as Ned then helps Ione with her plan to help famine victims by running a bring and buy sale, Ione’s confidence in herself slowly begins to grow . . .