Eight children, including three primary school girls, were found not at lessons during a crackdown by police and educational social workers.
The officers and council staff questioned a total of 37 youngsters during the patrol, the first of its kind in Harrow, on Thursday last week.
The three girls were taken back to their homes, and the remainder had their names and addresses taken so letters could be sent to parents and schools.
The sweep which included parks and housing estates as well as Harrow town centre followed the Government's Crime and Disorder Act which encourages local authorities to crackdown on truancy.
The sweep was partly hampered by heavy rain and neighbouring boroughs having teacher training days which meant that some children were legitimately not at school.
A Harrow spokesman said: 'This is the first time we have done this, but not the last. There will be another in May.'
He added that Harrow does not suffer a particularly bad problem with school absenteeism but, nonetheless, the council is determined to ensure that every child is in school.
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