Booklet Cylinder numbers - why bother?

I've now had time to scan the latest retail booklets (previously only publicity images were available). I am beginning to wonder why cylinder numbers are shown as we know that there are never any variations these days.

The English Locomotives retail booklet is unusual in not being printed with 4 process colours - at least I think it is printed in the actual colours; it's difficult to tell with the cylinders being printed on the dark green background!

 

The visible cylinder numbers, from the right, are Gold, Black or Green, Green or Black(both these look black!).  The less visible ones are the gold security overlay and phosphor which are above the LA of CLASSIC.

The 6th Olympic/Paralympics booklet which, being multicoloured, uses the normal process colours of (from left) Yellow, Magenta, Cyan and Black, plus light grey.  To the left are phosphor and gold security overlay, above the ond of London.