Damaged wing on an Airbus

[BarryP]

Turned up at Luton on Tues for a Monarch flight, walked out to the plane and noticed a large dent on the leading edge of the wing, halfway between the engine and fuselage, about 20cms long and 2.5-3cms in at the deepest point ! It had been covered in what appeared to be a shiny, aluminium type sheeting and then probably bonded on as there was no sign of any rivets. I was surprised it hadn't been taken out of service and repaired with this amount of damage, how bad does it need to be before they take a no fly decision?