This is going to be Coop and ASOS data only, so obviously there are some gaps to begin with. I think couple that with the fact that this weenie jackpot is most likely West Hampstead, they only have data back to 2004, so they've been pummeled in recent years and their normal isn't the full period that other sites are.
In just under 20 years of records they have 4 100" seasons and another at 98".