Hi guys - looked last night, not a broken belt but probably almost as catastrophic, the belt tensioner has completely fallen apart, ball-bearings dropping out of the cover etc.
Apparently she was doing around 70 when it let-go, but she swears there was no clattering/pinging noises - I guess that could mean that the valves immediately went hairpin shaped, OR if God and all his little angels love me, all of the valves were closed and stayed that way (just saw a pig fly past...).
Booked in to a local garage next week - fingers crossed - will keep you informed