Yes, the first line in both files was package ParseXLSX
I can see how Rolf's monkey-patching looks a bit safer than the way I did it so I will give that a go

Thanks for taking the time to write up this quick tutorial! It was pretty helpful to me
Now I think I can also see why sub-classing will not work in my application because I don't get to create the $P2obj on my own...
it gets created in the Spreadsheet::ReadData method.