Abstract: The present invention relates to an adjustable spanner (2) having a first fixed jaw (4) and a second moveable jaw (8). The second jaw (8) can be locked in fixed relation to the first jaw (4) by a locking means (16). This locking means (16) is moveable between a first position in which the second jaw (8) is fixed in relation to the first jaw (4) and a second position in which the second jaw (8) is permitted to move with respect to the first jaw (4).