Bike

I tried the twig on the bycycle lamp but she says "I might damage the lamp"so don't know if I've knocked it off or not,if I have can't find it on the ground?anyone?

If you knocked the lamp off it should be on the ground in front of that stage-like platform. The twig is the one you found at the Belvedere? I just finished the game, so holler if you need anymore help. Have you played all the Carol Reed games yet? I love them! Oh, I think the twig disappears from your inventory items when you knock the bicycle lamp off.

Is it the twig we picked up to make the sling shot with the elastic off the glasses?

No. While you are at the fortress you go up to the top and look out at the country side at all angles and you will find a building called the Belvedere. Carol will say that it is the tallest building. It will then be on your map. When you get there, look around until you find a pile of brush. Your twig will be in there that you use to knock off the bicycle lamp. Did you find at the fortress the clue about three green holes?