KGV 1d UV examples

hi skittlelinas -  sorry, have a feeling I'm going to fail you.      What you see in the attached pix is all I have of the 1d. - thought I had more, but I don't 'do' Oz and every time I get a page I usually give them away.      I also notice there is an obvious difference in these few insofar as the numeral is larger on some.       I know v. little about u.v. and stamps, other than the fact that some of the phosphor bands fluoresce, so am wondering what it is that I'm supposed to be seeing here - could be of course that my torch is the wrong nm wave length - I think mine is c. 390  -  day time is the wrong time to use the torch  -  night time is obviously better.       
Anyway, for what it's worth I have put these in the ottoman - stuck head in, holding camera and torch, whilst bring the lid down to simulate the dark  -  doubt though that they will be of any use for you.       I will try again late this evening to avoid need for sticking head in ottoman, and will let you know if there is any improvement.
Obviously you know about such things  -  so tell me, what is it - in/on the stamp - that reacts to the u.v. light  -  something in the ink?