11-01-2018 8:12 PM
You can buy large letter templates on ebay, worth buying 1 to check sizes before taking packed item to PO.
Mine is slightly under 25mm, so I know if it slides through, then PO will acccept it.
Look here:
I have the Royal Mail measurements in front of me and the size for a large letter is 25mm thickness, 353 x 250mm and max weight 750g.
My postmaster assures me that they are allowed to 'gently' pull the items through the cut out slot guides, however, the slightest resistance , then they have top charge for the next size, and that would indeed be, the small parcel size.
you must have mis-measured your package,
the post office 'slot' is 2.5cm thick,
a large letter cannot be more than 2.5 cm thick, 35.3cm long and 25cm wide,
if your package was bigger than this you had to send as a small parcel