If we change the year for CLT of 273,000 from 2017 to 2016 (to fit in the 7 years NRB), then the chargeable transfers calculated in the given answers end up being incorrect.
The CLT on 26/08/16 will be done before 17/09/16 so the annual exemptions for current year and previous years will be used by the CLT making its chargeable amount 267,000 & the PET of 47,000 will only be eligible for the marriage exemption making its chargeable amount 46,000.