Also tried my suit jacket on yesterday. When I last tried it on the sides were about 6 inches away! I put it on expecting something similar and it did up! I then tried on half of my wardrobe (the dark side, where I have about 20 t shirts still with their labels on that never fit) and everything either fit or nearly fit!. I have a Burtons XL shirt with the label on which was the tightest thing and looked a couple of stone away. That shirt has been mocking me for years and I will soon be wearing it!
Well done you!
I had a similar experiance last night...tried on a long leather jacket I wore when I was 14...it fastened!!
Nearly 13 years and multiple dress sizes later!