LONDON, Feb 4 (Reuters) - Even “quick fixes” to bank systems would take at least six months to be ready to implement any sub-zero interest rates, the Bank of England’s top banking supervisor said on Thursday. The BoE’s Prudential Regulation Authority, headed by BoE Deputy Governor Sam Woods, asked banks how much time they would need to get ready to implement any negative rates. Woods said in a letter to heads of lenders published on Thursday that a majority of firms said would need to make some changes to systems and processes to implement permanent changes or tactical or short-term workarounds. “On the basis of firms’ responses to this exercise, the PRA understands that the majority of firms would be able to implement tactical solutions to accommodate a negative Bank Rate within six months, without material risks to safety and soundness,” Woods said.