This is a collection of letters that children have sent into the programme over fifty years of Blue Peter put together by Biddy Baxter, the editor. I never sent a letter to Blue Peter myself, but I remember sending off for sleigh instructions and when they arrived I was convinced the letter had been addressed by Simon Groom (it wasn't, it was my Dad's self addressed envelope).
At one point Blue Peter were receiving over 7000 letters a week. Obviously not all of them are in the book but they're representative of the original, moving, often very funny, sometimes abusive, letters in which children (and `big kids') offered their ideas, pictures and stories providing a unique snapshot of life in the 20th century.
Marvellous stuff.