One final note comes from writer Greg VanWyngarden
"Hi. . . In "Der Rote Kampfflieger" MvR wrote of an Englishman who was one of a group brought down sometime circa March/April (I haven't time to figure it out). Anyway Richthofen and his boys talked to the Englishman: "He, too inquired about the red machine (Richthofen's D.III). It was not unknown to the troops in the trenches, who called it "Le diable rouge". The rumor had spread in his squadron that a girl piloted the red machine, somewhat like Joan of Arc. He was very surprised when I assured him that the alleged 'girl' stood before him at the time. He was not trying to make a joke; rather, he was convinced that only a maiden could actually sit in the garish crate."
That's part of the legend. Karl- Emil Schaefer started out in Jasta 11 flying a D.III with a black tail and yellowish ply fuselage (just as Wolff had his plum purple D.III in March 1917). However, in mid-April most of the Jasta 11 pilots painted all of their D.III types largely red. Schaefer's was apparently red with some black trim on the tail, etc.
When Schaefer took over Jasta 28 he still flew a largely red Albatros D.III, and this became very well known on the 4. Armee front; Max Mueller wrote that Schaefer was "taken for Richthofen here". On 4 June 1917, Jasta 28 tangled with Nieuports from No. 1 Sqn and SE 5a's from No 56 Sqn. Schaefer was apparently on the tail of Capt. Philip Fullard's No 1 Sqn Nieuport when Arthur Rhys Davids chased him off, and was credited with shooting down the red Albatros; Schaefer was indeed killed the following day, and somehow Rhys-Davids thought he had been killed on 4 June. At any rate, Rhys Davids wrote in his combat report: "All five of the HA , especially the leader (red fuselage, red, gray and black wings, V-strut type stuts, pilot wearing a gray fur flying hat) manoeuvred very well." In a letter to his mother he was more expressive: "For about 3/4 hour I played 'tic' with five of them, led by an extremely good pilot in a red, pink and grey machine. I wanted to go up and watch his flying instead of scrapping. . .Also, he seems to have been a sort of notoriety known as the 'Pink Lady' owing to the colour of his machine and his (presumably) bong qualities as a scrapper.'
There is a good deal of confusion in the descriptions of this fight, and Rhys Davids did not even put in a claim, but he got a confirmed Albatros due to the reports of the pilots of No 1 Sqn. On the next day when news of Schaefer's death circulated among the RFC pilots, somehow Rhys Davids became credited with his demise, at least for awhile.
So, I think the "Pink Lady" was based largely on sightings of Richthofen's, then Schaefer's RED Albatros. As has been commented on here, various angles of sunlight can do strange things to perception. The pilot who Johnnie Johnson was referring to was no doubt Schaefer.
That's my opinion.
Greg"