What would you have done in this situation? - Dangerous Drivers?

i know English country roads tend to be alot narrower than the ones we are used to in the US. i have to ride on the streets to get to the trails near me. my horse is usually totally comfortable with traffic and motorbikes and stuff, but i'm sure something speeding towards her would spook her just the same. so when i see a car coming towards or behind us too fast i try to wave them down like i needed help and then ask them to please go slower. some people are just clueless about horses and don't think about slowing. but every situation is different, just use your best judgement.