  We demonstrate a clear similarity between attoclock offset angles and
Rutherford scattering angles taking the Keldysh tunnelling width as the impact
parameter and the vector potential of the driving pulse as the asymptotic
velocity. This simple model is tested against the solution of the
time-dependent Schr\"odinger equation using hydrogenic and screened (Yukawa)
potentials of equal binding energy. We observe a smooth transition from a
hydrogenic to 'hard-zero' intensity dependence of the offset angle with
variation of the Yukawa screening parameter. Additionally we make comparison
with the attoclock offset angles for various noble gases obtained with the
classical-trajectory Monte Carlo method. In all cases we find a close
correspondence between the model predictions and numerical calculations. This
suggests a largely Coulombic origin of the attoclock offset angle and casts
further doubt on its interpretation in terms of a finite tunnelling time.
