Why did the British government’s opening of Giuseppe Mazzini’s letters cause public anger?

The British government’s decision to open Giuseppe Mazzini’s private correspondence sparked significant public anger because it revealed that the state was violating the privacy of individuals residing in England.1

The controversy intensified after the Bandiera brothers—followers of Mazzini—were executed following a failed revolt in Italy. Mazzini suspected that the British Home Secretary, Sir James Graham, had opened his letters and shared information about the brothers' plans with foreign authorities, specifically the Neapolitan government.21

When the matter was raised in Parliament, the government was forced to admit that it did indeed open private mail. This admission of state surveillance caused widespread indignation among the British public, who viewed the practice as an infringement on civil liberties. Although the accusation that Britain had directly facilitated the Bandieras' capture was later disproved, the scandal generated significant sympathy for Mazzini and bolstered his profile among English liberals.12