Building on the success of the two previous conferences held in 2017 and 2019 this conference will draw together the considerable community of researchers and practitioners who develop new mathematics of relevance to, and which underpin applications in Operational Research (OR). It will take a comprehensive view, it will showcase activity from across OR, and will welcome both contributions which have a clear application focus as well as those which are theoretically driven. Contributions will be expected to showcase both significant new mathematics and OR relevance. The conference will host plenaries from leading international experts. Invited Speakers Jakob Blaavand (The Smith Institute) Claudia D’Ambrosio (École Polytechnique, Paris) Kevin Glazebrook (Lancaster University) Nick Harris (Dstl) Dolores Romero Morales (Copenhagen Business School) Professor Edmund Burke (University of Leicester), President of the Operational Research Society will be giving an after dinner speech on the evening of the 22nd April 2021. Call for Papers Call for Papers: Papers will be considered for the conference based on a 300 word abstract for oral presentation. Abstracts should be submitted by Thursday 31 December 2020 via https://my.ima.org.uk/ Call for Posters: Papers will be considered for the conference based on a 300 word abstract for poster presentation. Posters are encouraged particularly from PhD students, and a prize for the best poster presentation will be awarded. Abstracts should be submitted by Friday 26 February 2021 via https://my.ima.org.uk/