From left to right: Common Footman, Scarce Footman, Dingy Footman, Buff Footman.
Of these Common Footman is by far the commonest, and the Buff Footman probably the most scarce. The Dingy Footman shows a wide 'melonseed' shape, so stands out versus Common Footman. Even for a Dingy Footman in the yellower colour form, the shape should help separate from Buff Footman. On the Buff Footman, there is a distinct 'crease' coming from the thorax down the center of the basal part of the forewing, and in the resting posture the back end always looks 'squarer' than on the Common Footman. The Scarce Footman pretty much speaks for itself with its tightly wrapped resting posture.
Credit: Mark Skevington