Can UK authorities arrest me solely based on an Interpol diffusion rather than a Red Notice?

Yes. Diffusions—sent directly between Interpol member countries rather than published centrally—carry equivalent practical effect in the UK. Police can arrest under a provisional warrant if the diffusion contains sufficient information about the foreign warrant and alleged offence. Unlike Red Notices, diffusions receive less scrutiny from Interpol’s General Secretariat before circulation, making them more vulnerable to abuse. Challenging a diffusion requires identifying its existence through subject access requests, then submitting deletion requests to both Interpol and the issuing country’s National Central Bureau.