Neil
The Champion WC548 plug caps come from
http://www.steadfastcycles.com/cart/ind ... ts_id=6420 (ignore their photo, they are black not gold). They are the only people who supply them with 'Champion' embossed although you have to add your own white paint. The ones from Green Spark Plug Co are plain. All UK cars after about October 1961 were fitted with suppressors which are separate from the plug caps and slide in. They are not reproduced but you can find them on eBay etc. Without the suppressors you will need the brass terminal clips:

Full details on spark plug caps, and which of the three versions goes with which build date here:
viewtopic.php?t=2006&postdays=0&postorder=asc&start=23 I would not recommend using any of these caps with the EDIS kit Ray supplied as he used silicone leads and the screw in connectors are unlikely to work, hence the moulded plug ends.
Andrew
The early cars used two circular Bakelite lead separators and a chromed ring to route the cables over the cam cover. The Factory deleted these and put the leads in a PVC shroud but continued to route them over the cam cover. They then decided to route the cables over the front of the cylinder head which was how it remained for the rest of production. IIRC dates of change-over were Nov 1961 and April 1962.
If you have any photos showing the red conduit on an E-Type I would be most grateful to receive them. As you say the shade does change and gets duller over time with the effects of heat and fumes. This is the one we gave to Julian as the basis of the reproduction. This one was over painted black:
