Thermal shutter system

A thermal shutter system comprising a plurality of elongate shutters (1), the shutters being mounted for rotation about the elongate direction thereof and being mounted for movement in a direction substantially perpendicular to the elongate direction, each shutter being movable independently of the other shutter or shutters for both rotation about the elongate direction thereof and also movement in a direction substantially perpendicular to the elongate direction, wherein the shutters (1) are rotatable to provide a first closed configuration, in which the ends of the shutters abut against a seal (11), and a second closed configuration, displaced 180° from the first closed configuration, in which the ends of the shutters are spaced from the seal (11).