The website only calculates postage approximately as there are nearly 100 different options on the Post Office price list. Some orders pay a bit more, some a bit less than they should! If you think you’ve been charged too much, please get in touch.
Brexit update:
The position with sending parcels to Europe has now settled down. Tracked parcels now go through without any difficulties because of the digital tracking system that the customs authorities prefer as opposed to the normal post route. It is now very rare that any charges are levied except occasionally on larger parcels.