Will resolve based on the Met Office's statement

"The definition that the Met Office uses to define a white Christmas is for one snowflake to be observed falling in the 24 hours of 25 December somewhere in the UK.

Traditionally we used to use a single location in the country to define a white Christmas, which was the Met Office building in London. However, with the increase in betting on where will see a white Christmas, the number of locations have increased and can now include sites such as Buckingham Palace, Belfast (Aldergrove Airport), Aberdeen (Pittodrie Stadium, Aberdeen FC), Edinburgh (Castle), Coronation Street in Manchester and the Millennium Stadium in Cardiff.

We also analyse the data from our observing stations around the UK to provide a complete picture of where snow has fallen or was lying on Christmas Day."

https://www.metoffice.gov.uk/weather/learn-about/weather/types-of-weather/snow/white-christmas