Tapping engine

Driving at 20mph approx. Tapping/ticking heard from engine area. Landrover Td5 2001 auto drives for another 30 metres before engine management light comes on, engine cuts out and I cruise to a convenient stop. Engine still turns over. At this point what's peoples diagnosis please?
Mechanic subsequently arrives, turns engine over several times before continually turning engine over before lots of metal grinding and clanking before timer chain smashes through rocker cover and engine no longer turns over.
Is a recon engine enough to repair?
Any advice????

could be numerous scenarios that cause cam to stop and chain to carry on ,but id look at a second hand motor with a warranty around 1k