[1] Klindworth's "illegitimate" daughter Agnes Street-Klindworth (1825–1906) was a lover of the musician Franz Liszt with whom she had a vast letter correspondence.
On 22 April the following year he tried to persuade the publisher Friedrich Arnold Brockhaus, as an agent provocateur, for the anonymous publication of a radical liberal-democratic article, but the plan failed and Klindworth had to leave Berlin after his dismissal on 4 May.
Klindworth then went to Paris and joined in 1832 for several years the service of French King Louis Philippe I, in whose secret cabinet, he played an important role.
In the 1840s, he was entrusted with diplomatic missions and agent jobs from the Austrian statesman Metternich, the British Foreign Minister Lord Palmerston, and other European princes and politicians.
Klindworth went from Stuttgart to Weimar, and in the following years he was assigned to various secret missions by the Russian Emperor Nicholas I and his successor Tsar Alexander II.