I understand that this subject has beat around in the threads of time. I am offering a link to a well known British parts supplier for their very comprehensive description of the brake and directional lighting system. There are companies selling bulbs, flashers, ballast resistors,etc...........They's guys have a video that walks you through a typical wiring diagram / electrical schematic and gives the technical details necessary for a successful LED conversion.
I understand they are selling parts, but they are putting facts out to us " Gear Heads "...........You be the judge.........Cheers
MossMotors.com - Restoration Parts And Accessories For British Cars
Pros= brighter safer brake lights, 30000 hrs life !!, available in red & amber
Cons= not weather resistant ( Shielding ?? ), $25/bulb