This is the rems of Bronsil or Bransill castle which was a seat of the Beauchamp family until abandoned by the Somers to build their play castle down the road http://www.herefordshire.gov.uk/htt/1166.aspx
It had been knocked about a bit in the civil war and the remaining tower collapsed in 1990 just as the scaffolding went up to stabilise it. The water is the innermost of the double moat that originally surrounded the castle and the ivy covered part an arched causeway