1959 BSA C15 ignition switch 63SA wiring up to a new Lucas wiring loom

[GRAY2wheels]

Hi, can anyone help with this one?
I bought a new loom and it has sockets for the lighting and ignition that go into pins on the back of the switches. My ignition switch is not like that - the wires connect directly to the switch. The light switch seemed to marry up quite well but the old ignition switch is a Lucas 63SA which has 6 wires connected to it with connections as follows

12 brown/white  from ammeter
13 purple to rectifier
14 white neg side of coil
15 black/white pos side of coil
16 green/yellow to stator
18 black to light switch

The new loom has only 5 connections to the socket
12A brown/W to rectifier and ammeter
13 W to coil -
15 black/W to coil +
17 G/Y to alternator
18 black to pin 5 light switch

Can anyone assist in where the 5 wires are to be wired to on the 63SA switch as I am trying to keep as much original as possible

[Bolti]

I have exactly the same issue. I cannot work out where the location of the purple wire that goes to the rectifier should be located.
Does anyone out there have a pin out diagram for replacing a Lucas 63SA switch for the later Lucas 88SA ignition switch please.
Bolti

[Bolti]

So people can someone help me on this C15 wiring with the purple wire from the rectifier and what to connect it to when using the 88SA ign switch.
Should I connect it up to the ammeter - does this work or is there another place I need to connect it too or do I just blank off the purple wire so it's not connected to anything.
What does the purple wire from the rectifier actually do?
Many thanks if you can help me I am sure someone must have been here before.

[JulianS]

This is the 1958 wiring diagram. It would probably have had some modifications in subsequent years.