Here's the thing - I have a horse and I ride a bike. My horse is an old lad now, been there and seen it all and is pretty much everything-proof, but even he will jump if a bike creeps up on us - mind you so do I! Bikes can be pretty stealthy and sometimes we don't know it's there til it's whirring past.
My preference as a horse rider is that a bike rider approaching from behind calls out (not the bell - that can be a bit startling) just to let us know he's there. Approaching from the front is no problem cos we can see him and as I say, my horse is very experienced. And sensible!
However if I was riding my bike and approaching an unknown horse I would call out and ask what the rider would like me to do, something along the lines of 'is your horse ok with bikes' and then do what I'm told! This is on the grounds that horses have great big steel-shod hooves powered by muscles the size of texas and hair-trigger instincts, all governed by a tiny little brain (bless them...
![Wub :wub: :wub:](/styles/default/xenforo/smls/wub.gif)
). And so do some riders (the brains bit, that is), and whatever the strict rights and wrongs of the case I would rather get by entirely without incident.
Whatever happens I would always put my own personal safety first - so if some stupid woman was waving me past her giant slab-sided sweating, plunging, eye-rolling nutter of a horse I think I would choose to decline and stop somewhere safely out of reach!
Sounds like your Duchess was a bit panic-stricken about what her young horse would do and didn't have enough spare processing power to be tactful. Whether I personally would choose to lead a green youngster while riding another, I dunno. You don't have much control unless you're on top.