(n.) a situation in which someone’s hopes or expectations are thwarted at the last minute
A Bloxwich bull is an instance in which someone’s plans or grand hopes and expectations are thwarted at the last moment.
Bloxwich is a small town in the West Midlands in central England, just north of Birmingham. Back when blood sports enjoyed a grim popularity much more widespread than they do today, Bloxwich was home to a bull ring and the highlight of the week for the locals in the town was the spectacle of a local prize bull being exercised in the ring and then slaughtered.
One fateful week, however, something unexpected happened—and at this point, we can hand over to the Victorian folklorist and antiquarian John Timbs to complete the story:
On another occasion, at Bloxwich, some wag stole the bull at midnight, and when the excited crowd assembled on the morrow, from all parts of the district, they were doomed to a disappointment. The circumstances gave rise to a local proverb still in use. When great expectations are baffled, the circumstance is instinctively likened to “the Bloxwich bull”. The remembrance of this barbarous pastime is perpetuated in the topographical nomenclature of the district, where, following the examples of Birmingham, almost every town and village his its Bull Ring.
John Timbs, Nooks and Corners of English Life (1867)