Has an election been made?: personal representatives
An election by the personal representatives is required if, and only if, the variation results in additional tax being payable, IHTA84/S142 (2)(b). The only likely case of additional tax is where property given by an original disposition to a surviving spouse or civil partner (IHTM11032) is, by a variation, directed to chargeable beneficiaries.
An IoV and a valid election can be made prior to the grant of representation being extracted (IHTM35032) but where the provisions of IHTA84/S142 (2)(b) apply and the personal representatives are party to the election you cannot accept that the IoV falls within IHTA84/S142 (1) until the grant has been extracted.
IHTA84/S142 (2) also provides that the personal representatives may decline to join in an election only if any assets that they hold as personal representatives are insufficient to meet the extra tax. In other words, that the requirement for them to elect does not require them to make any judgement about the merits of the variation, but merely protects them from liability arising from a variation after distribution. You should refer any difficulties arising from the requirement to TG at an early stage.