In reply to Phil1919:
Nope large estates are predominantly held in Trusts, so fiddling with IHT rates would make no odds. Others have suggested:
A land tax which thus can’t be dodged.
Tying all farming and land subsidies to compliance with the law, policy and conservation outcomes.
but you only have to look at ‘set aside’ on low land farms to see how if it’s possible the system will be ‘gamed’……pun intended.