I don't think a surface wind chart has ever caused me so much angst outside of winter cold spells - just look at how the flow takes the longest feasible track across the North Sea before turning to cross the UK!
While there's plenty of dispute regarding the temps modelled by FV3 (most of all), ECM etc - there's no doubt that it won't be nearly as toasty as it could have been for the CET region, even with the western bias to the monitoring stations.
A markedly warmer than average final week was a factor in my estimation for this month, as the tropical cycle looked to be very supportive after factoring in the typical delay of a week or so.
Frustratingly, that cycle has actually played out pretty much as I expected, and the very warm setup has essentially manifested too, but for an unusually strong ridge that could easily have extended less or more east, leading to much less moderation of temps by the North Sea.
You see with the scientific approach, it's certainly possible to get the overall pattern sequence right for the remainder of the month, but the finer detail can still kick you into the gutter anyway.
If one instead uses a mathematical approach, then the best approach for a low average CET errror is actually to routinely estimate close to the LTA unless extreme anomalies are predicted with high confidence (by the NWP models) for the first week or so.
I gather that this mathematical approach is what GW's hoping to deter by withholding the LTA stats until after the deadline.