Miners, banks weigh on FTSE 100; Tullow Oil plunges

(Reuters) - London's blue-chip stocks retreated on Monday as oil majors and Asia-exposed financials fell after disappointing exports data from China stoked growth worries, while midcaps were weighed down by a 50% slump in Tullow Oil.The FTSE 100 was down 0.2% by 0808 GMT, with its exporter stocks also taking a hit from gains in sterling ahead of UK general election later this week. The FTSE 250 also dipped 0.2%, with Tullow Oil single-handedly accounting for all of the index's fall in early..