An Iberia Express Airbus A320-200, registration EC-JFG performing flight I2-3617/IB-3617 from London Heathrow,EN (UK) to Las Palmas,CI (Spain), was climbing out of Heathrow's runway 09R when the crew stopped the climb at about FL130 reporting smoke in the cockpit. The aircraft diverted to London Gatwick for a safe landing on runway 08R about 25 minutes after departure. A passenger reported the crew announced smoke in the cockpit as cause for the return to London Heathrow, the aircraft subsequently landed in Gatwick however. Other passengers reported smelling smoke, too. Emergency services examined the aircraft after landing and escorted the aircraft to the stand, firemen boarded the aircraft to perform further checks. The passenger disembarked about 25 minutes after arriving at the stand. A replacement aircraft took them to Las Palmas the following day with a delay of 27 hours. A replacement Airbus A320-200 registration EC-JSK was dispatched to London Gatwick and reached Las Palmas with a delay of 27 hours. The occurrence aircraft was able to position to Madrid about 48 hours after landing.