Long story but found that indicators flashed quicker with one bulb removed - maybe 70% faster - but with Cobra brake LED in its place flashed normally. Then discussed with Duncan. He suggested despite my findings that I went for the canbus type as they have internal resistors - except he only had two! Then he did some current draw checks whilst on the phone finding canbus amber type draw 1.2 and normal ones 0.7 amp each. He's confident that with the tiny help from repeaters this will collectively present enough load for the electronic flasher within BCU to flash normally. Consequently has sent two of each.

Regarding your front sidelights would the same LED headlamp bulbs work with the ARV6 type headlamp lens as with Tony's car? Other suggestion would be to change front indicator lamps to BA15d double filament type. You could then use the white/amber LED's Duncan offers with auto switch over when indicators active. Clear lens would be needed of course.