A collection of invited papers presented to mark the 70th birthday of Professor Sir Alan Cottrell. Contents: dislocations and cracks; theory of the yield point and of strain ageing in steel; ductile and brittle failure in steel/pressure vessel assessments; dislocation reactions; the nature of grain boundaries in ordered alloys; radiation damage and point defects; 'the metallic state revisited'; microstructural characterisation of defects and mechanisms; creep and creep fracture; fibre reinforcement at the metallurgy laboratory at Cambridge 1958-67; strengths of grain boundaries in pure metals.