UNLABELLED: This paper presents subgroup analyses from the London Education and Inclusion Project (LEIP). LEIP was a cluster-randomised controlled trial of an intervention called Engage in Education-London (EiE-L) which aimed to reduce school exclusions in those at greatest risk of exclusion. Pupils in the control schools attended an hour-long employability seminar. Minimisation was used to randomly assign schools to treatment and control following baseline data collection. The study involved 36 schools (17 in treatment--373 pupils; 19 in control--369 pupils) with >28% free school meal eligibility across London and utilised on pupil self-reports, teacher reports as well as official records to assess the effectiveness of EiE-L. Due to multiple data sources, sample sizes varied according to analysis. Analyses of pre-specified subgroups revealed null and negative effects on school exclusion following the intervention. Our findings suggest that the design and implementation of EiE-L may have contributed to the negative outcomes for pupils in the treatment schools when compared to those in the control schools. These findings call into question the effectiveness of bolt-on short-term interventions with pupils, particularly those at the highest risk of school exclusion and when they are faced with multiple problems. This is especially pertinent given the possibility of negative outcomes. TRIAL REGISTRATION: Controlled Trials: ISRCTN23244695.