The REAL issue is the huge jump from zero percent IHT to a whopping forty percent on values over the relevant thresholds. That just causes reasons and motivations for people to take tax planning options to reduce or zeroise it.
It would be far better to start IHT liabilities with thresholds/reliefs at lower levels but then have a scale of IHT rates according to the amount of the estate in different bandings.
I.e. purely for illustration only...
O% on first £250k of an estate
10% on £250k to £1m
20% on £1m to £2m
30% on £2m to £3m
40% on estate falling over £3m.
That way there isn't the same "pain barrier" which is what usually causes people to jump through hoops to avoid paying any IHT.
As a result of the Budget, I've already had a few meetings with anxious clients, their solicitors and IFAs. These aren't farmers, but some people's estates are now facing a IHT bill of over a million when previously it was less than £100k, so the difference is massive. They were "happy" to pay £100k or less and weren't really taking any tax planning actions as the likes of trusts etc are expensive, but now they're facing close to a million, they're planning and will end up paying zero. So the "net" impact of Rachel's changes may well be less IHT collected as there's more incentive for people to take tax planning actions to avoid huge tax bills when they'd previously taken the view that relatively modest IHT bills were palatable.
As always, it's always the absolutely foreseeable consequencies which politicians claim not to have foreseen! They do it time and time again!!