The traditional stamp is soon to be replaced by a more secure, digital version using a barcode… which means existing 1st and 2nd class stamps must be used before 31st January 2023.
If you don’t think you will use up your supply before next January, there will shortly be the option to exchange current stamps for barcoded ones for free under Royal Mail’s new ‘Swap Out’ scheme, which opens on March 31, 2022 and will run until March 31, 2023.