Well access tool

A tool for gaining lateral access to a well via a lateral access passage, the tool comprising a head portion and being configured to axially forwardly advance the head portion towards or in the lateral access passage and being configured to transmit rotational drive to the head portion and/or to deliver fluid via a fluid transmission conduit to or forwardly of the head portion, and the tool comprising a first shaft and a shaft assembly comprising a second shaft, the second shaft being at least partly received in the first shaft so as to be axially forwardly movable therewith, whereby in use axial forward movement of the first and second shafts causes forwardly advancement of the head portion, and the second shaft being axially forwardly movable relative to the first shaft, the first shaft comprising an internal thread and the shaft assembly comprising an external thread engaging in the internal thread of the first shaft whereby relative rotation of the internal and external threads causes said axial forward movement of the second shaft relative to the first shaft without rotation of the second shaft relative to the first shaft, wherein the external thread is provided on a nut of the shaft assembly.