A jig configured to be positioned relative to first and second members, which extend along mutually transverse first and second axes respectively and are spaced along a third axis which is transverse to the first and second axes, for locating a hole-forming element with respect to the members and guiding the thus located element along said third axis during driving of the hole-forming element into the first member whereby a hold thus formed in the first member extends along said third axis for application therethrough, axially guided by the jig so positioned and/or the hole, of a connecting element to interconnect the members, such that first and second portions of the connecting element thus applied are received at correct positions in the first and second members respectively, the jig comprising: locators arranged to be received against the first and second members and rotationally about the first and second axes; and a guide defining an axis that is fixed relative to the locators (“guide axis”), the guide being configured to support the hole-forming element such that it extends along the guide axis and being arranged such that the guide axis is coaxial with the third axis when the locators are so received, whereby said driving of the hole-forming element forms the hole along the third axis.