Buy to let landlords have enjoyed 100% tax relief on mortgage interest for decades and only now, well in April 2017, are they finally about to start losing some of that unfair advantage over would be owner occupiers.

I'm not sure that it is unfair - since if a landlord's property is empty, they are liable for the council tax on it. It's a risk/reward scenario.

Consider a world with no landlords. You live with your parents until you can afford to buy, or you wait in line for social housing, which won't magically appear from nowhere...

Land is a finite resource, always in demand. I have zero sympathy for rent-seekers, and the government shouldn't be subsidizing the value of their assets.

And "emergency" low interest rates for 7 years or so. I imagine a fair fw of those would need to be sold if interest rates were at 5%.