(Reuters) -Sterling fell to a fresh 21-month low versus the dollar on Wednesday as Britain’s weak economic outlook and higher than expected government borrowing dented the Bank of England’s (BoE) monetary tightening narrative. Money markets have been scaling back bets on the size of BoE rate hikes, pricing in around 140 basis points (bps) worth of tightening by year-end from 160 bps last Friday. [IRPR] Data showed that government borrowing in the 2021/22 financial year was almost 20% higher than forecast. British retail sales slumped in April, with the first fall in volumes in more than a year…