More than 25 new junior police cadets met the borough's chief inspector for the first time.
Harrow police launched the Junior Volunteer Police Cadets for children aged 10 to 13 six weeks ago.
More than 30 children from schools across the borough have joined, and last night had a drill inspection by Harrow Borough Chief Inspector Gary Warby at Harrow High School, in Gayton Road.
The chief inspector said: “I have to say I am very impressed with all the cadets.
“They are energetic and what really shows they all want to be here and volunteer their time.
“It’s very encouraging to have had so many young people take an interest in the cadets and it will not only benefit them but also the whole community.”
Once a week the junior cadets meet at the school and take part in drill exercises, community projects and physical work.
It is hoped the new cadet force for the borough will train those taking part in mentoring and leadership.
The junior cadets is run by the Harrow senior police cadets, made up of teenagers from the age of 14 to 19.
The Volunteer Police Cadets is a uniformed voluntary youth organisation supported by the Metropolitan Police and has branches all over London.
Harrow High School chairman of governors John Courquin said: “I think the work the cadets do for young people is fantastic.
“For pupils from Harrow High that have taken part in the senior cadets we have seen a real improvement in concentration in the classroom and in exam success.”