The present invention relates to the completion of lateral well bores and provides a method comprising the steps of installing a datum device in a main well bore so as to provide a datum height above the lateral: making a completion string (10) comprising a lateral lining (11), a window element (14) at an upper end of the lining (11), a swivel joint (15) located between the lining (11) and the window element (14), and a datum device engaging member (21) located above the window element (14); running the completion through the main well bore and into the lateral; rotating the window element (14) to place the window at a desired angular position; and running the completion string home to engage the datum device engaging member (21) with the datum device.
