When I visited in early September 2015 cows were being grazed on the island. There are no formal paths on the island and I just walked around the edge of it. I disturbed a curlew and there were a number of plants in flower e.g. sea aster, sea lavender, thistles, sea mayweed, rosebay willowherb, dandelions and birds foot trefoil. I ate a couple of ripe blackberries off a bush. There are a few scrubby trees on the island - mainly elder and hawthorn - and some gorse bushes. I spotted a few samphire plants on the shoreline.
Rocky causeway linking Horse Island to the mainland
Sea asters in flower at Horse Island
Looking south west down the coast
If you squint very hard you may be able to see some cows at the far side of this field.