An oil drilling block managed by Tullow Oil at Lokichar basin in Turkana county, Kenya - Tony Karumba/AFP via Getty A London-listed oil explorer once celebrated for its exploits in far-flung waters is in danger of defaulting on its debts, credit experts have warned. Faced with having to make a giant $1.3bn (£1bn) bond repayment from a dwindling cash pile of less than $200m, Tullow Oil has suffered a further debt downgrade from S&P Global, one of the three main ratings agencies. The bond falls due in May ...