See also:
brodies.com/insights/pensions/inheritance-tax-on-unspent-pensions/
Update:
www.charlesrussellspeechlys.com/en/insights/quick-reads/102jp7s-the-future-of-iht-planning-with-pensions/
www.ropesgray.com/en/insights/viewpoints/102jpie/uk-pension-megafunds-the-tax-perspective#page=1