Cheers Ian, pretty much what I thought, i.e. should be almost no play. It doesn't idle near as well as it used to when new - it used to be absolutely smooth but is now "slightly fluffy" at idle, i.e. like most V8s but enough to annoy somebody like me maybe that is the cause, a bit of wobble in the timing.
I think an ordinary chain will probably see out the life of the car in my hands, even the D2 has too many ECUs in it for me to want to keep it into double figures, being a pessimist on all things electronic
I'm surprised it lasts such a short time though, its been religiously serviced at 6000 miles (often less - every six months) since new, and the interval on the Thor V8 is 12k using the synthetic oil, and it's not had a hard life.
By a stroke of luck, it was built when Rover still had an ounce of sense about parts commonality so I have discovered that the Thor chain is actually the same part number as even the old carb'ed engines, so I might find one yet...
Thanks