The thing I find curious about all of the (written) examples I've seen of an overhead join is that the aircraft depicted is conveniently always arriving from the live side of the circuit where you could perform a "textbook" overhead join. Is the implication, therefore, that before reaching the aerodrome you should position yourself so that this is possible?
For example, for the diagram given in the above CAA document, how would you make your approach if arriving from the south-east?