Actually, Britain is somewhat of an exception by this point. We already had a monarchy constrained by an assembly, and by 1832 the franchise to most property holders (not just owners). The later reform acts were really an extension of the process of extending and regularising the franchise.
If Britain had a particular impetus for Reform it would probably be the Revolutionary War which lost us the 13 Colonies, a war which itself sparked war in France. Both those revolutions succeeded, and I would argue that 1848 was a symptom of the groundswell that created rather than a major cause of change in itself.
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