LONDON, Dec 11 (Reuters) - The Bank of England took steps to keep banks lending through the COVID pandemic and the end of unrestricted trading with the European Union on Friday, saying it would keep a key lending buffer at zero through 2021. The BoE said that the counter-cyclical capital buffer - extra money banks must set aside during economic good times - would be held at zero until at least the fourth quarter of 2021, and that banks would not need to implement any future change until the end of 2022. (Reporting by David Milliken, editing by Andy Bruce)