New experimental photoabsorption cross section and angle-resolved photoelectron spin polarisation data for mercury are presented. For the first three autoionisation resonances above the Hg 6s threshold an analysis is performed in terms of transition amplitudes to the singlet and triplet continua. These quantities reveal that photoionisation dynamics is largely influenced by a rather complicated spectral behaviour of the triplet matrix element, including three changes of sign. Results are compared with quantum defect differences and ratios of oscillator strengths from the discrete spectrum.