He was a working class guy who made the right decisions at the right time.
bolded what was important... at one point he may have been but he clearly did well for himself and advanced his class... that is good, nothing wrong with that, but let's be real: he was not a working class person his entire time working.
opening his own firm, buying that kind of land - these are indications he was financially well off enough to be considered in the middle class. obv., without knowing the guy, I can't comment, but as soon as he made $10 mill even if he had somehow miraculously done all of that on low income before, he couldn't possibly be considered low income past that point.
even if he deposited his wealth in a bank account and never touched it, I would have trouble considering him to be truly in the working class, as opposed to an eccentric rich person.
edit: also I am assuming a surveyor is in fact a working class job, I have no idea what education requirements etc it requires... heh.