The allographic footnote is a key element of the peritext and a threshold where the translator and/or the editor make their voice heard. This article examines the translator’s footnotes in the Mercurio britannico, the Italian translation of the periodical Mercure britannique, published in London from 1798 to 1800, which played a significant role in the circulation of counter-revolutionary ideas. We speculate as to the functions carried out by the translator’s voice and whether the footnotes could be clues of his or her desire to “act politically.” To answer these questions, we first consider the editorial project and the political issues raised by the Mercurio britannico. We then introduce four types of functions performed by the footnotes, illustrated by several examples. Emphasis is placed on the multiple functions of this liminal space and, more generally, on the dynamics linking translation and the circulation of political ideas. Finally, we reflect on the results of our analysis and suggest some avenues of further enquiry.