Why did they ever add it?

I guess the short version is “linux developers don’t use macs, so they don’t know what it means for everything to Just Work”.

If you won’t let my children inherit, I can will to them. So you have to prevent post mortem gifts. But what is to stop me making an inter vivos transfer (perhaps using a scheme like a trust to make it all work the way I want)?

Ultimately you would have to abolish alienability of property. That is a very interesting approach but hugely revolutionary and requires considerable thought on your behalf.

Of course we toyed with non-alienability of land prior to Quia Emptores (1290). At that time you would have needed your feudal Lord to agree to the transfer and, at an earlier time, to any inheritance. But land is much easier to organise this way than other kinds of property and other kinds of property are now very important.

Also: where do you think we got the idea for trusts _from_ in the first place?

I understand that some principle of non-heritability was used by Aztec nobles, but I do not know the details and of course it is entirely possible to reduce the affection for children (cf Sparta) which might have an effect.

Uphill struggle anyway.

Inheritance tax is, of course, not a tax on inheritance. Despite the name, it is a capital transfer tax, it is just that the rollover relief is automatic until death.

There was a recent episode of Clive Anderson’s “Unreliable Evidence” on iPlayer about this, but it’s expired. A lot of it was discussing vulnerable people who believe that there’s some sort of “common law marriage” in England, which there absolutely is not.