Probate and Blighted property

[rodhake]

How does a blighted property be valued for probate purposes and would it be acceptable to assume that blighted/ unsaleable property can be given a valueless amount for IHT?
The property in question will be affected by HS2 and will have value in the future if and when the Government commits to the proposed extension to Manchester but at this present time it can not be sold and thus has no value.
Probate value is at the date of death and the property is unsellable so the value can only be established in the future depending on governmental decisions.
Any advice would be gratefully received

[AGoodman]

That sounds correct to me with the caveat that the property is not entirely unsellable. Presumably an investor might pay (say) 25-50% of the usual value to benefit from an upside once the decision has been made.