With respect, weather has nothing to do with it. If you look at Royal Mail website it clearly states:
Last post second class 18th December
Last post first class 20th December
Item was bought well in advance of those dates and if the seller bothered to look he/she would know that 23rd was too late. Again, poor customer service. Just MHO
Best wishes for Christmas everyone and hopefully great sales for the New Year
Kind regards
Alan
PS I am off to have a few Christmas drinks with friends tonight by tomorrow night I might be a bit worse for wear