“The Sultan of Brunei has a Boeing 747 with solid-gold sinks and gold-plated everything.”

Hassanal Bolkiah, Sultan of Brunei since 1967, is a qualified pilot and has owned a fleet of large aircraft including Airbus A340s, a Boeing 767 and the 747-430 that acquired the nickname 'the Flying Palace'. The interior, by all accounts, includes a master suite, guest bedrooms, a dining room and lounge, with gold used liberally on taps, handles, trim and basins.

Purchase price is reported as at least $100 million with a further $120 million on the fit-out, though as with all such figures the sourcing is thin. The Sultan has occasionally flown the aircraft himself to regional summits, a fact that reliably astonishes the aviation press.

The technical reality punctures the myth a little: 'gold-plated' means micrometres of gold over brass or steel. Even the crystal-and-gold washbasins would weigh a fraction of what one first-class galley cart does. The exotic part of the aircraft is its ownership, not its metallurgy.

The Sultan has more recently taken delivery of a Boeing 747-8, reportedly with a similar treatment, keeping the title of world's most opulent private airliner in the family.