I have my Disco back from Ritters in Melbourne. The bill was rather more than I thought but then it always seems that way these days.
The problem was a pressurized sump. Hats of to Mark Draper who in reply to my original post said it would be a head gasket failure between #4 pot and #8 pushrod hole. The service manager at Ritters told me the same thing when I arrived with the car.
Spot on Mark.
Ritters provided a curtesy car a Holden Commadore which decided it didn't want to go any more and that I should walk home from the shops. As I was picking up the Disco the next day Ritters arranged a tow truck and a lift the next day. To anyone in Melbourne I would recomend them to Ritters. Not cheap but they know Landrovers as that is all they do.