Can you shed any light on the...

The British counterpart of this phrase is “hell for leather,” meaning in a hell of a hurry. Evidently, the phrase was coined while the British army was in India, and most likely the leather refers to a horse’s or team’s leather gear, from saddle to bridle and reins, and the whipping given to these items when a rider or driver was pressed to attain full galloping speed. “Hell-bent” is an American term, meaning headed in a certain direction at all costs and with heedless speed, even if it means ending up in hell. Most likely, “hell-bent for leather” is a combination of these two phrases.