jOe, the fact you posted photos of a sleever here tells me you get 'em after the maintenance has been done. Everything I need to know about a sleever can be summed up thusly-leave it for you.
You make it sound as if it is rare to find a 100 year old English gun that needs work. Quite the opposite is true.
Some needed more than others, it would seem, just going by that beautiful "SLEEVED" stamping on the top of the tubes of your Purdey. Not sure why Weiand didn't turn and run from that Hussey (17 large, and still counting, at the end of the article, and that didn't include the price of wood or the price of admission for buying the gun) but, that isn't my type of story.
Not sure why you didn't run from that sleever, either. I mean, before you bought it.
Best,
Ted