Thanks everyone, it's off now. Used Excel's tube and hammer approach for the top rivet, but had to use Midlife's file technique for the lower one because there wasn't enough metal on the inside of the rivet for the hammer technique to work.
Was a pretty nerve-wracking experience, was afraid the wafer thin bit of brass at the end of the badge would not hold up,
but I was very careful and got away with it. Its from a bike from 1928 so it's not like I could replace the badge with a new one if something went wrong.
Will probbaly use RobbieD's tip when it comes to replace the badge.
Thanks for the tips.
Johnny