Localisation for magnetically actuated robots is essential for their accurate control and delivery of functionality. With the advent of new magnetic actuation platforms based on multiple external permanent magnets for actuation of complex continuum robots, new localisation techniques that account for these additional sources of magnetic fields are needed. In this work, we introduce a novel 6 degree of freedom localisation method without the need for any prior pose information. The method is based on a 3D accelerometer and magnetic field sensor in the Special Euclidean Group SE(3) and is compatible with multiple magnetic field sources platforms. The algorithm was demonstrated on a dual external permanent magnet platform achieving norm position errors of 8.5mm and 3.7 degrees in orientation.