In the UK, the maximum compensation for lost or damaged luggage is governed by the Montreal Convention, which sets a limit of approximately £1,350 to £1,400 (roughly 1,288 Special Drawing Rights) per passenger. If your bag is not returned within 21 days, it is officially "lost," and you can claim for the current value of the contents. It is important to note that airlines do not pay "new for old" prices; they calculate depreciation, meaning you’ll receive only a fraction of what a three-year-old suit or laptop originally cost. For delayed baggage, you are entitled to reimbursement for "essential" purchases like toiletries and basic clothing, provided you keep all receipts. If you are carrying high-value items like jewelry or professional camera gear exceeding the £1,400 limit, experts recommend making a "Special Declaration of Interest" at check-in (for a small fee) or relying on a dedicated travel insurance policy, as the standard airline liability is rarely enough to cover luxury belongings.