I believe in the 747 era, National ran them to London 3 days a week, and DC8s the others. Whether this was a regulatory capacity restriction or just reflected what they thought the demand would be, especially in winter when their size better suited the JFK-Maimi route anyway, I don't recall. When the smaller DC-10-30s came along they ran daily. The leased DC8s lasted for quite some time, from 1969 to 1974.
I believe the two 747s were initially named "Europe" and "Florida", but just a few months later National's well-known girls' names and slogans campaign came along to the whole fleet, and the 747s were changed.
Although it was quite some time between National arriving and the Bermuda restriction on airlines at Heathrow, it was the start of the thought process from the UK side. It had always been accepted that it was two US carriers there, Pan Am and TWA, versus BOAC. Once a third carrier came in, and particularly once they started marketing onward connections to points already served by both established US carriers, like Los Angeles, the arrangement started to be found unreasonable. It had always been felt to be a shoo-in for Pan Am, strong at both ends of the route, and was a surprise when the Nixon administration selected National instead. How did National's charismatic CEO Lewis B Maytag, heir to the Maytag US appliance fortune (he also owned US local service carrier Frontier at the time), manage it with Tricky Dicky ? It was a Presidential administration decision on foreign carrier licences. Bureaucracy though takes a long time to move. National used to advertise in the UK these flights and connections every day in a long-running small sidebar ad on the front page of The Times newspaper, different destination each time.
Airlift themselves, like National based at Miami, bought a few civilian-standard Hercules in these times, and did very well with them rush-ferrying replacement big fan engines in their early unreliable days for all of Pan Am, Eastern and National from their major Miami maintenance bases out to AOG widebodies scattered around.
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