The trial of single operator towing was carried out at Heathrow late at night some time around July or August 1998. The tractor units were fitted with folding arms each mounted with a strobe unit of something like 4000 cd each which were filtered aviation red and aviation green. These were set so that they would shine up and illuminate the two sides of the aircraft with a pool of high intensity light in an approved colour and so ensure that the aircraft could be easily seen and recognised from all angles without the on board nav/anti-collision lights.
As for the comment about not being able to see the aircraft from behind, at the time of the trial someone to the rear of the aircraft would have been facing a combined flash power of 7-8,000 cd, which is in the region of 18 times more powerful than a standard red strobe.
What happened after this I don't know as I changed jobs shortly after and lost touch with the project.