Photopolymerizable composition

A photopolymerisable composition comprising at least one polymerisable ethylenically unsaturated material and a photosensitive catalyst comprising

• a. at least one photosensitizer having the structure ##STR18## wherein the groups A, which may be the same or different, are hydrocarbyl or substituted hydrocarbyl groups, and wherein the groups A may be further linked together by a direct link or by a divalent hydrocarbyl group or wherein the groups A together form a fused aromatic ring, and
• b. at least one reducing agent capable of reducing the photosensitiser when the photosensitiser is in an excited state, the reducing agent having the structure ##STR19## where M is an element of Group Vb of the Periodic Table of the Elements and the units R, which may be the same or different, are hydrogen atoms, hydrocarbyl groups, substituted hydrocarbyl groups, or groups in which two units R together with the element M form a cyclic ring system, no more than one of said groups R being substituted hydrocarbyl groups, no more than two of the units R being hydrogen atoms and the element M not being attached directly to an aromatic group R.