Answer:
When you need me, you must find me. When you find me, you no longer need me. What am I?
In a tunnel of darkness lies a beast of iron. I can only attack when pulled back. What am I?
You cannot keep me until you have given me. What am I?
When I get closer my tail grows longer but when I go away my tail leads the way.
I am a celebrity fish.
I met a man on the London bridge, he tipped his hat and drew his name, in this riddle I told you his name. What is it?