The Office for Budget Responsibility has brought out a short report on the proposed changes in inheritance tax for farmers and in Business Property Relief: https://obr.uk/docs/dlm_uploads/IHT-APR-and-BPR-supplementary-release-Jan-2025.pdf
It is necessarily a very technical report, but the main takeaway seems to be the uncertainty associated with the revenue yields which are the stated main objective of the policy. In other words, the political cost may outweigh the financial gain. Some would argue that changing the rollover relief for selling land for development would yield more revenue and cause less pain.
Meanwhile a number of major supermarkets, most recently Tesco and Lidl, have declared their opposition to the proposed reforms. Of course, words are cheap and major supermarkets have been squeezing farmers margins (or worse) for years.
Farmers are notoriously slow in many cases to put succession plans in place, but could be allowed more time to do so, while the precise calculation of the threshold for liability is complex but needs further examination.