Eeenk -
There you go!
Wiki (and the like) research may be 'tedious', but in today's Listener environment it's absolutely b***** essential; for instance, you say that you and your wife had a full grid but for a very long time couldn't name the colleagues - you must therefore have both early been aware that four 'chimaerical' cells symmetrically placed contained 4 very distinctive thematic items different in kind from those in all the other cells. Surely your wife must have been intrigued as to their significance? Had she entered them in the obvious order (or if the order wasn't obvious, as permutations) into Google, or Wiki, the colleagues' names would have immediately appeared. (Note: the
Title is
not the Theme.)
Ditto with last week's puzzle, which you say you're stuck on, in spite of having a full grid; I'd go so far as to say that it is impossible to solve last week's theme without consulting Wiki - the very specific imagery required is absolutely arcane and cannot be guessed. Even though I was very familiar with the theme, without being nudged repeatedly towards very specific imagery on Wiki I would not have been able to complete.
I used to pride myself on solving cryptic crosswords totally unaided by dictionaries - but when I started The Listener I realised that reliance on Chambers is not a weakness but a necessity - and given the number of obscure words, always has been. With the availability of electronic apps and online reference encyclopaedias, the thematic ingenuity of setters has, I'm sure, increased to the point where the whole battery of research engines is not only permissible, but essential.
So - swallow your pride and consult the oracles!