Human rights campaigners wore Kenneth Clarke masks and chanted slogans as part of a protest against a tobacco firm's investment in Burma.
Burmese nationals joined the protest against BAT
The demonstration focused on the MP for Rushcliffe, Nottinghamshire, who is also deputy chairman of British American Tobacco (BAT).
Campaigners demanded the company close a factory in Burma which it jointly owns with the country's military dictatorship.
A BAT spokesman said the firm respected the concerns of protesters but it was not willing to take on a "role of international diplomacy".
Campaigners carried placards quoting a letter from Mr Clarke to one of his Nottinghamshire constituents in which he said he felt uncomfortable about investment in the country.
I know of people being paid just pennies for a day's work - it's worth fighting for
Tun Tun, Burmese protester
John Jackson, director of Burma Campaign UK, which organised the protest outside the firm's London headquarters, said: "We are not going to let Ken Clarke off the hook.
"BAT are collaborating with a military dictatorship."
Protesters from the Burma Campaign were joined by Unison representatives and members of the Burmese community.
Tun Tun, 26, from Burma, who has lived in London for four years, said: "When these companies invest in Burma it's over for the Burmese people.
"It's so bad and painful for them, they suffer for profit.
"I know of people being paid just pennies for a day's work - it's worth fighting for."
The firm said it respected the campaigners' views
The protest on Wednesday was the first staged by the Burma Campaign UK against BAT although it has been running a postcard campaign since last November.
A BAT spokeswoman said: "We understand and greatly respect concerns about human rights.
"However, we do not believe that the best way forward is for businesses to withdraw from countries whose governments' human rights record have been criticised.
"Campaigners may suggest that business can influence how countries are governed.
"While we are willing to discuss these issues open-mindedly with stakeholders, we do not believe businesses should take on the role of international diplomacy and that companies do not and should not have a mandate to step into areas of political authority."