In post-war Briain there was a huge merchant navy fleet, almost all oil-fuelled by this time, which picked up bunkers all around the world sometimes thousands of tons at a time. There was also the RAF whose aircraft fleet dwarfed the penny numbers of civilian airliners, and of course the Navy, who needed their own ocean-going tankers to keep them fuelled between ports. I doubt the consumption of foreign exchange for commercial Avgas came very far up the financial radar at all.