Exhaust Gasket Issues

My exhaust is a mix and match from over the years and the cat pipe's flanges are a different size to the front pipe/cat back sections of the exhaust. The last time we changed it we thought we had got it working OK as i don't want to spend money on it if eventually i will replace it with a flat underfloor.

Unfortunately it was the night before i headed to Wakefield so i made do with a used gasket but this was what had happened to the last one.