The phrase "correcting a statistically determined artificial jump in the data" used in BOM's explanation for the "homogeneity adustments" to the Rutherglen recordings is one of the starkest examples of circular self-justification I've read for long time.
And I'm someone who accepts a causal link between climate change and human activity.
It's no wonder the conspiracy theorists jump on this kind of nonsense. "Statistically determined" just means the output of a model based on someone's assumptions based on opinion. The extent of the "correction" will have been based on someone's opinion.
Another completely circular self-justification: "As AGW was not an issue back then, the importance of tracking all changes and impacts on temperature records were not relevant back then."
We have come to the conclusion that there is AGW. We do that on the basis of records. But some of those records have an "artificial jump" which we found as a consequence of a statistical model. We therefore have to "correct" those records. The "errors" were there because the people who made the records did not know about AGW. Once "corrected", the records support the conclusion that there is AGW.