IHTM10154 | Other assets due to the deceased: compulsory acquisition of land
From HM Revenue & Customs · Inheritance Tax Manual
You should not normally consult the Valuation Office Agency (VOA) (IHTM23002) if either
a notice to treat (or deemed notice to treat) had been served and a price fixed before the valuation date for inheritance tax purposes, or
the acquiring authority had entered on the land under statutory powers and a price had not been fixed by the valuation date.
You should refer any case where the amount of compensation (of which the value of land is a component) was not agreed by the valuation date to the Technical Actuarial Team.