I don't see a byline for the article, so I can't Google to see what sort of connections to the UK real estate industry that the author has. Oh well.
http://www.economist.com/blogs/economist-explains/2013/09/ec...
https://andreaskluth.org/2008/11/20/why-the-economist-has-no...
Generally, I imagine they're reputable enough that they should disclose any conflicts of interest, but who knows...
Personally I think raising taxes on second homes, rentals, etc would free up a lot of housing to purchase. Do we want to do that? Are people happy renting and not buying? I'm not sure.
Why would they be trying to advance these policies?
2) The price of the land is passed on to property buyers in its entirety.