By Ali Lyon The Chancellor would be breach of her own fiscal rules if interest rates fell just 30 basis points less than the fiscal watchdog forecasts, Office for Budget Responsibility (OBR) economists have said. Giving evidence to the Treasury Committee, OBR member Tom Josephs told MPs that his colleagues conducted an analysis that found “a change of the effective interest rate of 0.3 per cent..” was all that was needed for Rachel Reeves to break her spending pledges. “A one percentage point increase in interest rates adds about £16bn or so to borrowing,” Josephs added. The Chancellor chose t…