Ask H&H: high-visibility clothing

Q: IS a rider’s insurance cover affected if high-visibility clothing is not worn? Does the use of the words “Caution — young horse” on the back of a high-vis bib in any way impact on a rider’s insurance cover? Are there any insurance industry guidelines for what might constitute an acceptable standard for high-vis gear on the rider and/or the horse? And would the use of a defined “industry standard” suite of high-visibility aids attract a discounted premium?

GJ, Somerset