Answer
You should first contact your bank or credit card company and report the loss to them. They will then advise you to contact Police Scotland (dial 101) to report the loss and get a lost property number.
It is imperative that you report the matter to the bank first, as the card needs to be stopped so that it is not used. In theory, the most you will have to pay if your card is used without your knowledge from being lost is £50, although this may vary from bank to bank. However, if you were negligent then it may be that you will be liable for all the losses.
Many banks and credit card companies offer Credit Card Protection schemes which means for a relatively modest fee you only need to report the loss to one company and they will notify all other credit card companies and banks on your behalf