LONDON, Oct 18 (Reuters) - Bank of England Governor Andrew Bailey said risks to economic growth in Britain were skewed very heavily to the downside, and reiterated that he expected economic output at the end of September to have been 10% lower than a year earlier. “Ten percent is still a huge gap, let’s be clear on that,” Bailey told an online seminar for central bank governors hosted by the Group of 30. “We’re operating at an unprecedented level of economic uncertainty. Of course, that is heightened now by the return of COVID.... The risks remain very heavily skewed towards the downside,” he added. (Reporting by David Milliken, Editing by Paul Sandle)