@Dave the Gnome:

"Have you never heard that a rich man will always want more? Do you really believe that earning £7m would stop a rich landowner from kicking a poor family out on the street to earn an extra £100 a week in rent? I am not saying that Haig was such a man, but to rule out the possibility that he wanted more money is, at best, naive and, at worst, dishonest."

The type of rich man you describe above is the sort that started out with nothing and acquired wealth. The sort of person who values money above all else. Haig's chosen career was as a soldier - so that simply does not fit, it does not gel or make any sense.

Haig was not a rich landowner, his family distilled whisky and made a very good living out of it. Had Haig been interested in money he would have gone to the family business and expanded and diversified it. The fact that he did not, the fact that he remained a soldier, tends to indicate that Haig had little or no interest in acquiring wealth.

You seem to consider "possibilities" yet ignore "probability". Lots of things are "possible" most of those things however can be ruled out when "probabilty" is taken into account. A man in NEED of money might risk his social standing and his reputation by "ripping off" a charity (That is both "possible" and "probable") much less "probable" is a man with wealth, position, reputation, recently honoured by the nation ever doing so.

If such a rumour was ever in circulation, and so far only Raggytash has ever heard it, then I would say that Allan Conn's explanation of what gave rise to it is the most likely. I would also have thought that the rumour would have been strongest in and around Edinburgh and the borders as people would have to have known about the house being built to comment on it.