This is an Oxford MPhys project undertaken by J J Dudek. `Variationally improved perturbation theory' (see S K You et al, Eur. J. Phys. 19 (1998) 179-186) is applied to the potential -a/r + br, which is relevant to heavy quark-antiquark systems. The problem provides an instructive `laboratory' for undergraduate exploration, and there are further possibilities to be pursued. The results are published in I. J. R. Aitchison and J.J. Dudek, Eur. J. Phys. 23 (2002) 605-614.