Description of characters in Goodnight Mr Tom?

Its about a young boy named Willie Beech who is an evacuee during world war II. He is evacuated to the country and falls under the care of Tom Oakly, while he is staying in Little Weirwold he meets his soon to be best friend Zach at the post office who is cheeky and bold. Willie is a sad deprived child but he slowly begins to flourish and reveals his true talent as an artist, but all this changes when a summons from his mother ruins it all :O