I am grateful to commenter "hmc" for pointing out that David Quarmby has also produced an audit on the country's response to the start of the cold weather a month or so ago. This includes some further interesting information about the Met Office's advice to government:
The Met Office gave ‘early indications of the onset of a cold spell from late November’ at the end of October, but detailed forecasts of snow were not possible until a few days before the first precipitation. The amounts of snow were generally well captured, although in some areas were considerably underestimated by some weather forecast providers.
I find the quotation marks at the start of this excerpt particularly interesting. What this suggests to me is that Dr Quarmby was advised that such an "early indication" was given, but that he didn't see it himself.
I've emailed to check if this surmise is correct.