Hi Sarah, I had a similar thing happen to me about 25 yrs ago, only I wasn't near horses at the time. Was walking to my mums along this road near a runway for HMS Daedelaus' planes and it was about 11.30 at night, I heard horses hoofs on the gravel and saw this huge horse just casually eating the grass along the verge. I went into my mums and said it looks as if a horse has escaped from somewhere, we both went out to see if we could catch it but it was gone, no sound, nothing. When we spoke to a neighbour the next day, we were told it wasn't unusual for people to see this horse as it was killed not far from where I saw it. So sad