[Boxybutgood]

Thanks all for responses and sympathy!

To answer a few questions;

1; New thermostat fitted by MD (at my request...)

2; Temp gauge never indicated overheating; as the expansion tank showed no evidence of overflowing, and the cough was on the day I discovered the issue, I am confident (not legally helpful I know) that I found it on the day it happened. No coolant had been lost. It was transported to the MD and was not driven from the time of discovery. On arrival they said it started fine, no cough, though after they replaced the thermostat it ran poorly when hot. It clearly has overheated and I suspect that the sender is in the part of the engine that may have been starved of coolant so the temp gauge was of no help. The MD hasn't suggested that the crack was a consequence of being driven with a failed thermostat, but that the crack may have occurred beforehand due to age/mileage (155k). This is of course more difficult to disprove than arguing that the damage was my fault because I drove it with the temp gauge showing a problem; if I had driven any distance the engine would have completely overheated and probably seized

3; Last Jan is Jan 18.

I'll think on over the weekend as to my options, but thanks again for the advice re an engineer's report before I start proceedings.