P contracted D to design a chimney for them. The design was faulty and at a certain date P discovered damage to the chimney. P sued D and the question was from what period damages were accruing. P claimed damages from the point at which the defect occurred, whereas D claimed that they ought to accrue from the moment of discovery or first moment when they could be reasonably discovered. HL allowed P’s claim for damages accruing from the moment that the defect was caused.