There are three Royal Mail Retail Compensation Policies, covering different issues that happen to the shipment.  Below are the specific details.
Compensation for Delayed shipments
The compensation is valid when delayed shipments occur. In terms of  Royal Mail Special Delivery Guaranteed by 1 pm, if the recipients haven’t received the parcels after 24 hours of the due date, the sender can claim the compensation. Additionally, continual compensation might occur when the parcels have not been delivered or attempted to ship after 7 working days of the due date.
Compensation for Lost Shipments
The compensation for the lost parcels applies to the situation that the recipients haven’t received the parcels after 5 working days of the due date and there is no evidence to prove the parcels have not been lost. Saturday would be considered as a working day when Saturday Guaranteed has been purchased, otherwise Saturday, Sunday, or public holidays are not defined as working days.
Compensation for Damaged or Partly Lost Shipments
The compensation for damaged or partly lost parcels for Royal Mail Special Delivery Guaranteed by 1 pm would be paid when an item of the parcel is damaged to the extent that needs to be repaired. The claims for damaged or partly lost shipments should be made before 80 calendar days of the posting day.