FTSE hits session high after Draghi weighs in

(Reuters) - London's main stock index rose to a session high on Tuesday as a promise of more stimulus if need be from European Central Bank chief Mario Draghi added to boosts for the miner-heavy index from rises in copper prices. The main FTSE 100 index, up only marginally in the first minutes of trading, jumped half a percent after Draghi said the bank would need to ease policy again if inflation did not head back to its target.The FTSE 250 midcap index also recovered some ground but was still..