As any youth growing up in Oshkosh, WI is taught, the answer to “The World’s Busiest Airport” deserves an asterisk, at least for one week each summer. That week is the time for the annual Experimental Aircraft Association (EAA) Fly-In. The amount of air traffic, mostly small planes and military aviation, easily surpasses Chicago O’Hare’s traffic as measured by landings and take-offs.
Heathrow is pronounced heath-row.
Only ‘colourful cockney characters’ beloved of old movies would drop the initial H & pronounce the th as f.
I’m not a pedant - in the strict interpretation of the word