I too, was somewhat puzzled by the large NEGATIVE reaction to this morning's BOE's rate hike... At minimum, I expected a quiet "non-reaction" since the hike itself has been telegraphed by the BOE for weeks...
Her assessment was that this rate hike was NOT the start of a hiking cycle (ala US-Fed policy) but rather just a "one-and-done" deal... An assessment bolstered by the BOE's own projection of ONLY two rate hikes over the next 2-3 years. (...in many analysts' views, the BOE did a "Cover-Your-Ass" move to negate last year's emergency post-Brexit rate cut)
As such, traders/investors punished the GBP across all major currency pairs (GBPUSD, EURGBP, GBPJPY)
-----------------------------
So, what's the lesson in all the above..? When trading the news, ALWAYS try to look beyond the headline numbers... Sometimes, price action will seem "illogical", but that's only because there's a deeper logic to be found.