The paper describes a novel, highly elongated, ellipsoidal shell tokamak (EST) configuration which has favourable high pressure magnetohydrodynamic Mercier and bellooning stability properties for a range of shell geometries. Calculations of the magnetic field (|B|) contours also suggest that an EST can be broadly omnigenous. The considerations leading to the choice of an ellipsoidal shell configuration, the equilibrium and ballooning stability properties and the axisymmetric stability are discussed and the parameters of a sample design for a modest proof-of-principle EST are presented.