Started and drove the vehicle about 800m, no problems, stopped at traffic lights and battery warning light came on, turned out of junction and heard a clank and dragging on the road, stopped car immediately and when I looked underneath oil was pouring out. There was no vibration or any other warning. Belt was fully intact, only saw two bolts, one bent and the other thread was stripped. Called breakdown assistance who towed car to garage.
Apparently crank pulley hit pipe on the block of the engine and has caused damage which requires engine replacement.
Sorry its not very technical but I know very little about cars but this is how it has been explained to me!