We spotted this on the site of the old Anchor brewery near London Bridge, round the corner from another plaque spotted by Jeff/Stonch a while back.
According to Thrale.com (“Anything and everything Thrale or Thraill”), here’s the story:
The Austrian General Haynau was notorious for the brutality with which he put down rebellions in Hungary and Italy. So… when the word spread that the ‘Hyena’ was in the brewery… he was attacked by draymen and brewery workers with brooms and stones, shouting ‘Down with the Austrian butcher‘. Haynau fled along Bankside pursued by the angry men and took refuge in the George pub… from which he was rescued by the police with difficulty, and spirited away by boat across the river. The Austrian ambassador demanded an apology, but the Foreign Secretary Lord Palmerston sided with the brewery men, saying they were just ‘expressing their feelings at what they considered inhuman conduct‘ by a man who ‘was looked upon as a great moral criminal‘. Only after the intervention of a furious Queen Victoria and the threatened resignation of Palmerston was a more conciliatory letter sent to Vienna. Even then Austria was still so resentful that it sent no representative to the funeral of the Duke of Wellington in 1852.