Originally Posted by Horseybex
I think she's bay roan...
The mane's brown in the first picture but it looks black in the last one and she's got black stockings on her legs, consistent with the bay colouring.
She looks a similar colour to a pony I ride who is bay roan too.
Bay and brown are both mutations of the agouti gene. They both restrict black pigment production to the points of the horse. So both bay and brown horses have black on their legs, black on their ears, black manes and tails - the "hard" points, or the extremities of the horse. The difference between the two colours is in the "soft" points - muzzle, flank, under the tail, in the elbow. On a bay horse, these would match the body colour. On a brown horse, the "soft" points are lighter than the body colour.