Well I would have requested an upgrade to club, that is rearely full. There is no way i would have parked my posterior in pee . Unbelievable !

There is no way I would have sat there. It surely is easy to replace the cushion.

Pretty grim - how does that even happen though?

It happens apparently by paying a pittance to Mixed Fleet crew , alongside scrapping free sandwiches and drinks on short haul flights and outsourcing your IT according to Unite as reported in the Daily Mail story

http://www.dailymail.co.uk/news/article-4806026/Businessman-given-seat-urinated-BA-flight.html

In my opinion there are failures along the way , on the turnaround you would expect the seat to be dealt with if it was soiled , secondly, you make sure the cleaners are responsible to make sure it's put right , you inform the customer and if you have no other free seat available ( which apparently was the case and not mentioned in the DM report ) you make sure they are adequately recompensed or that a clear report goes to head office to contact customer and they get the correct response first time .