"I wouldn't expect the effect of the unwind, of QT (quantitative tightening), to have a material impact on the economy. So far our experience with the beginning of the shrinking of the portfolio is consistent with that," Tenreyro said at a conference hosted by King's Business School in London.

Since February the BoE has not reinvested the proceeds of government bonds that have matured from its portfolio. BoE staff are due to report to the Monetary Policy Committee on options for active bond sales next month.

(Reporting by David Milliken; Editing by Mark Porter)