Canvas - Sprite small...

I have a canvas, inside the canvas is a Rect Transform acting as a Container for HudDisplay which is a panel. I instantiate a gameobject that contains a sprite and set it's parent as HudDisplay.transform. When this happens, the sprite is very smalll.... it's local scale is 1,1,1 I'm not sure I understand why when I drag the same gameobject directly into the Canvas hierarchy it appears the correct size but when I set it's parent as the HudDisplay panel it's tiny....

Canvas is confusing!!!!