We want to better understand the structural modifications and short-range correlations in ferroelectric triglycine sulphate near the ferroelectric phase transition. Above the Tc, one of the gycine molecules is disordered across a mirror plane. On cooling the glycine chooses one side of the plane. Diffuse scattering can tell us how the molecule averages about the mirror plane above Tc. Does it sit on the mirror plane with large amplitude oscillations or hop between wells on either side? Both cause changes in the conformations of adjacent molecules but with different distributions of interatomic distances. Diffuse scattering gives two-body correlations, so can probe the distribution of interatomic distances and distinguish between the two possibilities. Also, above Tc, there is short-range order in the polarisations of molecules that can also be examined using diffuse scattering.