CGT Chattels disposal

Trustee of a Maintenance Fund Trust. Some chattels have been lost and conditional exemption lost as a result, we have paid the IHT for the loss of the conditional exemption with a settlement date of 2023 but the items value used as 2011 as agreed with IHT team. We are in the process of making an insurance claim. If the insurance claim is successful when is the disposal date for Capital Gains Tax? the date the chattels were last seen (1998), the date they were documented as lost (2013), the IHT conditional exemption ceased (2023) or the date of receipt of insurance proceeds (potentially 2024) In addition if the insurance claim is not successful is it still possible to record the Capital loss.

Hi R NE,
Please see general guidance here on deemed dates of disposal:
CG14260 - Computation: rules determining date of disposal
and
Calculation of loss
Further guidance on Heritage Maintenance funds can be found here:
TSEM5800 - Heritage maintenance funds
However, as per guidance at:
IHTM11260 - Exemptions: conditional exemption
It may be worth contacing The Heritage Team.
Further guidance on capital taxation can be found:
Guidance on capital taxation and the national heritage Updated 9 May 2022
Thank you.