Just got back form the engineers (took my shells to show them), they agree either it's been started with no oil in, or going by the deeper score marks in the shells there was dirt in between the shells and the crank!
They recommend a complete strip down, cleaing of all engine parts, flushing of all oil ways to remove any remaining swarf, and have also said that my cam may be damaged because of swarf embeded in the journals, the con rods will need resizeing because of heat distortion and that the crank is probably scrap because it's been reground to 0.25mm oversize already!