[Graham G3ZVT]

Hi David,
Nothing as subtle as an Ishihara Test at Granada Rentals.
When we went to the training department at Amthill Rd in Bedford to do our colour induction, there was a Thorn 2000 high on a wall bracket witch was wired back to the lectern and the teacher could demonstrate all sorts of faults.
The first thing he did was to put each primary and complimentary colour on the screen one by one and we had to write down what we saw. I'm pretty sure that anyone who failed got their P45.