A period of uncertainty

A discretionary trust's assets included a reversionary interest in a life interest trust i.e. an entitlement to that other's assets on the death of the life tenant who died in November 1998.
The discretionary trust had a ten-year anniversary inheritance tax charge in June 2005 and the calculation of that charge has regard to additions in the previous ten years which include the reversionary interest. Whilst the additional assets (cash) were not actually received until November 1999 and March 2000 it was the November 1998 date of the death of the life tenant on which the discretionary trust became entitled to the other trust's assets and that would seem to be the date on which it became relevant property of the discretionary trust.
At the time of the life tenant's death in November 1998 the inheritance tax position of the trust in which...