Abstract: Well apparatus comprises a tower, and a support for supporting well intervention, completion, testing, or drilling equipment, the support being attached to the tower and being movable laterally from a parked position on the tower, where preparation of the equipment can be carried out without occupying an operational area where the equipment is to operate on the well, and an operational position in the operational area, and the support being arranged to be lowered or lifted, the apparatus further comprising a guide mechanism for guiding the support so that as the support is - lowered or lifted it is guided along a path involving lateral movement from the parked position to the operational position in the operational area.