Matters such as a rate of interest deliberately included by the parties in an order drawn up and sealed by the court do not constitute accidental slips or omissions within the slip rule under CPR 40.12. It was entirely within the scope of the court's intention for the parties to agree the precise terms of the order as to interest. The court should be very cautious before going behind an apparent agreement between counsel. The rule will only apply in such circumstances where the order had an unexpected and unintended effect inconsistent with the court's intention (Leo Pharma A/S v Sandoz Ltd www.bailii.org/ew/cases/EWHC/Patents/2010/1911.html).