Pre-eruptive magnetic field configuration in relation to the CME eruption and radio emission. a–c: PFSS field lines generated from the GONG synoptic magnetogram for CR 2126. d–f: PFSS field lines plotted over the pre-eruptive configuration, as observed at 171 Å by STEREO/SECCHI/EUVI and the Sun-Watcher with Active Pixel System and Image Processing (SWAP; Seaton et al. 2013) instrument onboard the Project for On Board Autonomy 2 (PROBA2; Santandrea et al. 2013) spacecraft. g–i: PFSS field lines plotted over difference images of the CME eruption, as observed by STEREO/SECCHI/EUVI and SDO/AIA, overlaid with the radio centroids from Figs. 3a and 4e–f.