Analysis of Playmates

It's sixty years ago, the people say:
Two village children, neighbours born and bred,
One morning played beneath a rotten tree
That came down crash and caught them as they fled;
And one was killed and one was left unhurt
Except for certain fancies in his head.
And though it's all so very long ago
He's never left the wood a single day;
I've often met him peeping through the leaves
And chuckling to himself, an old man grey;
And once he started in his cracked old voice:
'We're playing I'm a merchant lost his way,
She's robbers in the wood behind yon tree,
The minute we grow up too big to play' -