The invention is useful for upgrading a mechanical handle assembly to an electronic handle assembly without the need to remove the handle from the door or the like to which the handle is attached. The handle assembly (100) is of the type which is mountable to a surface of a door. Handle (18′) is moveable between a locked position and an unlocked position. A first housing useful for a mechanical locking handle is replaceable by a second housing (80) during conversion of the handle assembly from a mechanical version to an electronic version. Handle (18′) is received at least partially within the housing (80) and is substantially within housing (80) in the locked position. In the unlocked position, handle (18′) protrudes from the housing (80) and can be cause to swing sideways. Opening of the door when handle (18′) is in the locked position is prevented by a lock (24′). When converted to the electronic version, lock (24′) may remain but is capable of being unlocked by electronic actuation means (44, 78, 82).