Hi ramseyoptom,
Thanks for your reply, that's informative. Yes, I have found that I can sometimes see or not see different Ishihara plates under different conditions - they only really seem to be able to tell you whether or not you have colourblindness, rather than how bad it is. I am one of the people who never knew they actually had a problem until they took the test, and I like the idea of doing a lantern test, but you have to go to Gatwick, right?
Anyway, I'm sure a lot of people similar to me come on here and ask the same questions so I would like to thank you again
