You can see where the cutting disc has marked the paint. It hasn't been burned off. The 'spatter' looks to me like build up from someone using fairy liquid to check for leaks.I hate to say it but in my opinion that has been cut off with an gas torch,hence the paint removal and spatter on the tank and trapped where it has been cut off.If it had been cut with a grinder, the cut material would travel away from the tank.
It's stamped till 2022.As far as I know, Gaslow stopped using shrouds about 2005. In which case, a bottle which originally had a shroud would be over 15 years old and should really be binned.