Furring strips?

[OBonio]

Down the side of our front window, we have what appears to be a metal strip coming away from the wall. From my research thus far, I think it is a furring strip used to help the plasterer when the house was built.

Is there any way of getting this plush against the wall again? I've tried super glue with no luck. How about drilling a hole in it and tacking it down? We're redecorating at the moment and would love to get this sorted before we start painting on it.
Many thanks for any help.