ACR iCard Lost ACR card! Seeking advice before I go to immigration office.

The post above stated that it was needed to apply for the ECC clearance, not at the airport.

Advice on locking the barn door after the horse is stolen: don't carry around your card, it's only ever needed at an immigration office and it's difficult to replace. Get a driver's license for i.d. They are cheap and easy to replace, in my experience. Keep the immigration card safe with your passport.