reveals an unexpected link between Bacon and the photographer Lartigue:
"... Bacon's resort to photography, both still and cinematic, was constant, obsessive and over-the-top. Its sources and results have an enormous span, from the relatively familiar – Dr Goebbels orating, terrified crowds scattering from the tsar's police, or the bloody face of the nurse on Eisenstein's Odessa Steps, peering hysterically through her broken spectacles – to the utterly obscure. There are bits of Picture Post and images from those resources of gay porn, the body-culture magazines of the 50s. Sometimes the obscure details lie within images themselves famous. For instance, there is a well-known photograph of a racing-car at Le Mans, in which the speed of the machine and the panning camera movement turn the wheels into forward-leaning ellipses, distorted cartoonwise. So striking is this effect and so dominant the machine's image that few people so much as notice the figures in the background, on the verge of the track. But Bacon did, and he stole a pair of them, enlarging them for the right panel of Crucifixion (1965), where, in their odd soft hats, they look threateningly like a pair of Australian yobs leaning on a bar."
The ‘well-known photograph’ of a racing car sounded mightily familiar, and sure enough, a quick Google reveals that Bacon had borrowed the figures from Lartigue's racing car photo for the right panel of his triptych: