I dug out the book with Lowell's own account and typed it up. Hope that adds to the confusion
Clearly it's an XIV and clearly it took place in July 44 based on the 51s about to arrive.
Dan/Slack
John Lowell, Quoted in the book "Top Guns" by Joe Foss and Matthew Brennan
"Our group received several P38Ls just before the P51s arrived. This latest Lightning had dive flaps under the wings, improved power and a gun camera located away from the nose. On a day we were stood down, General Eisenhower arranged for one of the top English Aces, Wing Commander Donaldson, to come to Honington and show us slides of English Spitfires that had been equipped with external tanks loke US Fighters. Those tanks allowed Spitfires to penetrate deep into Germany. Most of the US pilots didn’t know about the Spits long range, and some of the Spitfires had been fired upon before American pilots realized their insignia was the Royal Air Force and not a German Swastika. ME-109s, P-51s and Spitfires were not easily distinguishable from one another until close enough to make combat.
All the 364th Fighter Group Pilots attended Donaldson’s slide picture presentation in our briefing room. When he finished, he described the new Spitfire XV he had flown to our base. It had a five-bladed prop, a bigger engine, and improved firepower. Then he said, “If one of you bloody bastards has enough guts, I’ll fly mock combat above your field and show you how easily this Spit XV can whip your best pilot’s ass!”
The entire group started clapping and hollered “Big John! Big John!”
That was me, so I asked him, “What is your fuel load?”
He replied, “Half petrol.”
“What is your combat load?”
He said, “No ammo.”
We agreed to cross over the field at 5,000 feet, then anything goes. I took off in a new P38L after my crew chief had removed the ammo and put back the minimum counter balance, dropped the external tanks and sucked out half the internal fuel load. I climbed very high, so that as I dived down to cross over the field at 5,000 feet, I would be close to 600 mph. When Donaldson and I crossed, I zoomed straight up while watching him try and get on my tail. When he did a wingover from loss of speed, I was several thousand feet above him, so I quickly got on his tail. Naturally he turned into a full power right Lufbery as I closed in. I frustrated that with my clover-leaf, and if we’d had hot guns he would have been shot down. He came over the field with me on his tail and cut throttle, dropped flaps, and split-Sed from about 1000 feet. I followed him with the new flaps, banked only about 45 degrees, but still dropped below the treetops.
The men of the 364th were watching this fight and saw me go out of sight below the treetops. Several told me later that they though I would crash. But they were wrong!. All I had to do was move over behind his Spit XV again. He was apparently surprised. He had stated at our briefing that he would land after our fight to explain the superior capabilities of his Spit XV, but he ignored that promise and flew back to his base."
