Background The Triple P parenting programme has been reported to improve child mental health at population level, but it consumes substantial resources. Previous published work has suggested improvements in whole population scores in the Strengths and Difficulties Questionnaire (SDQ) Total Difficulties Scale among samples of children following introduction of the programme. This paper aims to explore whether Triple P had an impact on child mental health problems using routinely collected data over 6 years before and during the implementation of the multilevel Triple P programme in Glasgow City. Methods Annual monitoring of teacher-rated SDQ Total Difficulties Scale scores among children in their pre-school year in Glasgow City. Results No significant or consistent changes in SDQ Total Difficulties Scale scores were seen during or after the implementation of Triple P programme on a whole population level. Conclusion Triple P in Glasgow City appears to have had no impact on early child mental health problems over a 6 year period. The Triple P programme, implemented on a whole population level, is unlikely to produce measurable benefits in terms of child mental health. Electronic supplementary material The online version of this article (doi:10.1186/s12887-017-0800-5) contains supplementary material, which is available to authorized users.