Subject

Founded at a meeting in Almack's / Willis's Rooms, when 280 Whig, Liberal, former Peelite and radical MPs met to agree on a strategy to remove Lord Derby's Conservative government.

The Guardian reports, at the unveiling of the plaque: 
Duncan Brack, of the Liberal Democrat History Group... said of that meeting a century and a half ago: "Among those attending were Lord Palmerston, John Bright and Lord John Russell – and the meeting paved the way for the political ascendancy of Liberal prime minister William Gladstone."
Davis described the occasion as "momentous" and said: "When Palmerston, Russell and their Radicals, Peelites and Whigs coalesced around the issue of Italian reunification, at this very location in 1859, I am sure everyone expected the union to be a temporary one. For generations British political life has been fluid, with numerous changes of government, factions and minority administrations. However, for what was then such a disparate union, the Liberal party has endured, helping to shape so much of British politics since. And the timing of this unveiling could not be more appropriate, as its successor – the Liberal Democrat party – once more finds itself in government."

The Liberal Party merged with the Social Democrats in 1988 to form what became the Liberal Democrats.

Note: The Radical Club is said to be a precursor to the Liberal Party.