Note the one-piece rotor and magnet ring, the magnets being in the wider ring at the base of the rotor (on the left, standard rotor on the right). This differs from other manufacturers who seem to supply just the magnetic ring with their triggers, a standard rotor going on the top. The complete thing was cheap at £50. Normally the triggers themselves are around £90 (Magnetronic and Aldon) although considerably cheaper from Pertronix at about £60, and with points distributors typically being about £80 new David didn't get a bad deal anyway even taking into account having to retro-fit points and a condenser.

Subsequently Gary Falkiner pointed me to this ETC5835k from various Land Rover specialists sold as a conversion kit using the original distributor. This image (from Britpart) looks pretty-much identical. Although this initially seemed to work OK it became inconsistent, and was picking up iron filings on the magnetic collar, so Gary has gone back to points as well.

Optronic trigger wire with strands broken inside the insulation and causing an intermittent misfire: (Ben Columb)