Andy, the interesting thing about the number of kids dilemma is your use of the word "fair". Comparing two families with houses of the same value but different numbers of children makes the current system seem unfair, but how about comparing them both to a family with a home with ten times the value, and a family with very little by way of assets to pass on to the children? The only way to make sense of inheritance is to see it from the dying person's point of view, to argue that they ought to be allowed to pass on a chunk of their earnings to other people. As soon as you argue from the child's point of view it all falls apart, you get led down the path of state redistribution of all inheritances.

There are better ways to ensure children have a decent start in life, as well.

I agree about buying to let, it's another contributory factor for sure, especially where I live in south London! We regularly get letters through the door from estate agents encouraging property owners to let to yuppies (as though we're not worthy of living there any more). Most houses that go on sale have a "to let" sign outside them a week after they've sold!