there is a new lighting circuit on the new single storey extension, but now there is also a new conservatory going in next to it, how is the wiring done to put in 2 wall lights on the old exterior wall, i know how to wire up to ceiling roses, but how do you do it to wire up to wall lights, can the old lighting circuit be broken into with a junction box (or are these outlawed since 17th edition). obviously you cant have incoming, next light, switch wire and wall light going into the wall light. hows it done please