Background: Having a stammer can have a significant effect on a child’s social, emotional and educational development. With approximately 66,000 children in the UK having a stammer, there is a need to establish an adequate evidence base to inform clinical practise. We describe a feasibility trial to explore the effectiveness of a new therapy programme for children aged 8-14: Palin Stammering Therapy for School Children (Palin STSC(8-14)). Preliminary data from the Michael Palin Centre, where the programme was developed, indicate that Palin STSC(8-14) is effective in reducing stammering frequency and impact for children, with beneficial effects for parents too. We will investigate the feasibility of the methods required for a definitive randomised control trial to investigate the application of this therapy by NHS speech and language therapists (SLTs), compared with ‘treatment as usual’ (TAU), beyond the specialist context in which it was developed.Methods: This is a two-arm feasibility cluster-randomised controlled trial of Palin STSC(8-14) with TAU control arm, and randomisation at the level of the SLT. Quantitative and qualitative data will be collected to examine: the recruitment and retention of therapists and families; the acceptability of the research processes and the therapeutic intervention; the appropriateness of the therapy outcome measures. Assessments will be completed by children and parents at baseline and six months later, including measures of: stammering severity; the impact of child’s stammering on both children and parents; child temperament, behaviour, peer relations, anxiety; quality of life; and, economic outcomes. There will also be a qualitative process evaluation, including interviews with parents, children, SLTs and SLT managers to explore the acceptability of both the research and therapy methods. Treatment fidelity will be examined through analysis of therapy session records and recordings. Discussion: The findings of this feasibility trial will inform the decision as to whether to progress to a full-scale randomised controlled trial to explore the effectiveness of Palin STSC(8-14) when compared to Treatment as Usual in NHS SLT services. There is a strong need for an evidence based intervention for school age children who stammer. Trial registration: ISRCTN. ISRCTN17058884. Registered 18th December 2019. https://www.isrctn.com/ISRCTN17058884