Although even if it does get to the top there are quite a few similarly wet Winters, so not "unprecedented" at all.
If it gets to the top of the list of wet winters it WILL be unprecedented in terms of wet winters
Because that's what the defintion of unprecedented is
The definition of un-precedented is nothing similar having preceded it. The list shows several similarly wet winters occurring throughout the 150-odd years recorded.
If it gets to the top of the list by, say, 10 or 15 cm, then everyone would agree it's a record, but few people would feel they'd experienced something they'd never experienced before (a lousy, wet and windy UK winter with flooding on a very minor scale compared with e.g. 2007 in Yorkshire or 1919 or 1703 on the Somerset Levels).
If it gets to the top by 100 or 150 cm, then perhaps we'd see effects without precedent, because the next 12 days would have to have been, well, unprecedentedly horrendous.
But so far we've seen nothing of that scale. Just weather consistent with the English climate and nothing inconsistent with the English climate.
2 miles west of Taunton, 32 m asl, where "milder air moving in from the west" becomes SNOWMAGEDDON.
Well, two or three times a decade it does, anyway.