The Prime Minister may still be in two minds about his backing for a third runway at Heathrow Airport, but 100 look-alikes are more certain.
Protesters against airport expansion, many from the borough, gathered in a park in Hounslow on Saturday wearing Gordon Brown masks and false ears.
The Government is due to decide the runway question this month.
BAA, which owns and operates Heathrow Airport, has announced it plans to ask the Government to appoint an independent assessor to guarantee public confidence in noise and air quality limits if expansion is approved.
Colin Matthews, chief executive of BAA, said: "We have listened to the many arguments around expansion at Heathrow. Although the economic case remains compelling, we under-stand that we can only increase the number of flights if we can safeguard levels of noise and air quality.
"By calling on an independent assessor to scrutinise the airport's performance against these limits, we are providing an uncompromising assurance that we will operate Heathrow Airport within the limits laid down by Government."
His words have angered No Third Runway Action Group members, whose chairwoman Geraldine Nicholson said: "This is just another promise set to be broken.
"Mr Matthews kept saying it was a question of trust. How right he is, and quite frankly, we don't trust anything that BAA says."