Before I start this lecture, let me say that The choice of whom society honours is one for society as a whole, and not the mob. I don't want to lose that in what follows
// Jim, An either/or hasn't been suggested. [It] is hypocritical to demonise the founder whilst enjoying the fruits of his beneficence. //
I don't see the hypocrisy because the two are easy to separate. The sole purpose of a statue is to glorify a person. If it were historical then each statue should be accompanied by as detailed a summary as possible of the life and works, including the flaws, of the person it honours, but since in some cases you've objected even to that then I don't see that the preservation of history is really the aim here. In the case of a hospital, in particular, the presence or absence of a statue of the founder has literally no impact on the quality of medical care. As a result, the debate over its presence or absence can clearly be kept entirely separate from the presence or absence of the hospital.
A few other points that trouble me:
1. I don't really "get" the defence that somebody was judged innocent, or not judged at all, in their time. The slaves on the slave ships knew that what was happening to them wasn't acceptable, so the standards you are judging people by ends up being incredibly biased. It's the "history written by the victor" defence, in a slightly different but equally dodgy guise.
2. Very often it seems like the order in which events are learned shapes your view of whether or not a statue could be deserved. If the first thing you learn about Thomas Guy is that he funded a hospital then "of course" he should have a statue. If you only later learn that his money was of dubious moral origin then... well, that's exactly the debate we are having. It's mitigated because of the good thing you learned first. If you learned about his life story in the other direction you might, and indeed probably would, see things differently.
3. History is subjective and it's pointless to pretend otherwise. Statues in particular are a very visual expression of this: they are a subjective choice, made of a particular time, expressing who the society of the day wishes to honour. There is no reason in the world that a decision made of its time must be perpetually respected, regarded as immutable. What about the many people that, consciously or otherwise, our ancestors chose not to honour? Often very deliberately, too? Are we obliged to respect their wishes in that, too? I should imagine not; people who used to be vilified by flawed ancient (and not-so-ancient) standards are now rehabilitated to take their deserved place in history. Think of people like Turing, who was treated literally as a criminal in his lifetime, and quite shamefully too.
Whilst we're on that subject, it is, if I may say, interesting too to look back on previous debates on the topic and see the following snippets:
"Homosexuality was never wrong, but the law that deemed it to be wrong was ... We have 'undone' [this wrong] ... [and in any case] there has been no suggestion of ‘undoing history’."
At the same time you rejected analogies about apologies/pardons for harsher punishments, in cases of "crimes that were detrimental to society". What more detrimental crime is there than slavery?
[snippets taken from
https://www.theanswerbank.co.uk/News/Question1518883.html ]
To me, this suggests that you'd accept the principle that we can judge people in history by our standards rather than the standards of the time in cases where the law was clearly and unambiguously an ass. I don't see why the logic that suggests that someone convicted of something that should never had been criminal should be now rehabilitated, apologised to, the damage "undone", etc. cannot be reversed.
I'd like to end this where I started, though, and say that none of this means I support vandalism in any sense. The choice of whom society honours is one for society as a whole, and not the mob.