A Grate or Gully is an open drain with grate designed to overflow outside if a sewer blockage occurs (the opening must not be obstructed).
Speaking with Neil Mills on site, I felt if I went ahead with the purchase I would be up for major expense in having the faults he specified rectified by various specialists in their field. His detailed and comprehensive report confirmed my decision to terminate the contract. As much as I liked the house, yard and location, it needed too much work and money spent on it to justify the purchase. I'm going to rent for a while and take my time looking for the "right" home. I will certainly be contacting ABIS again and asking Neil to carry out my next inspection. Thanks again Neil.