Mackay also gave legs to a fair number of more or less hoary myths himself. For instance it's taken years of scholarship to debunk the alleged "tulip mania" in 1630's Holland (Ann Goldgar's "Tulipmania" casts a cool and sceptical eye over the whole business) and historians who should know better still recycle the myths Mackay put into circulation in the Anglophone world. His account of the South Sea Bubble is full of myths recycled from the equivalent of the tabloid media of the day. To put it charitably, he could be very uncritical of his sources

In other words I'm not sure I'd count him as a debunker of pseudohistory- indeed quite a bit of the time he was effectively playing for the other side.