Based on its own projections, Capital Economics has predicted that the headroom against the UK’s public debt rule could approach £29bn, although it expects the OBR to come up with a smaller number. However, Ruth Gregory, deputy chief UK economist at the consultancy, stressed that even modest changes to the OBR’s forecasts would be sufficient to “wipe out the headroom”. “Even a small pre-election giveaway could leave the chancellor’s fiscal rules on shaky ground,” she said.