Right. Mr Vauxhall neighbour got under the car last night. He said before I even started it up, is it making a mad hissing noise so he had an idea already. He reckons it is a pipe of some description that has split. We are going to jack it up this evening to have a proper look. He said its not a blocked DPF as that is at the front of the engine and exhaust gases are getting out under the car by what looks like a flexi pipe. So in essence I have no idea what has happened but he does.