Same here. The highway code has sections that walkers, runners, cyclists etc. should adhere to if they're in the carriageway. If they're going to be tossers and disregard their end of the deal, I shall be a tosser and disregard my endGorgon wrote: If the cyclist is a gentleman's sausage and decides he's going to ride home after work/whatever on country roads or main roads with no hi-vis clothes, then I generally pass them like a gentleman's sausage.
if they're doing everything they should be doing to make motorists' lives easier then I treat them courteously in return 
horses are another story, the family are all into them and if you spend enough time in the countryside you'll probably see what a car looks like after hitting something the size of a horse... Screw that for a game of soldiers. As a rule of thumb, for pedestrians and cyclists I pass them with at least half a car width to a full car width depending on how the road allows and without slowing. For horses, I slow to a crawl and pass using the throttle as gently as possible. I used to ride, and horses are stupidly unpredictable and have a flight instinct so strong they regularly run into harms way just because of a noise they don't like or something they see that scares them, bloody stupid animals Give them a reason when you pass them, and they will kill themselves, their rider, and quite possibly you too 
On a slight tangent, I don't agree with any use of roads with a 50mph+ limit by cyclists/pedestrians, the closing speeds are ridiculous and it's not fair if someone has to live with hitting somebody they couldn't avoid when they were travelling within the speed limit.
I'm not sure how relevant my answer is, sorry
