Google gives contradicting results, so I thought I'd ask academics... Which one is the correct one in British spelling? Also, should I spell whichever way the authors spell, then mention the spelling differences somewhere in the thesis even if I won't be doing any direct quotes? Or should I stick to one spelling throughout my thesis, and consistently use that? I guess that would also need some explaining in the text?

Name of the key-character of my research is also spelt in two different ways in different publications. I am also in two minds about what decision to take about the use of spelling in my thesis, so my question goes for that too.

Thanks in advance...

I have a range of different terms in the literature, for the same construct - and this happens for several other constructs too. I've decided to have a brief 'terminology' page, which just goes through the slight differences in what they all mean and the reason and definition of the term I've decided to use. Then I have been consistent all the way through the thesis (e.g. called it abc), even if researchers have reported it using a different term e.g. xyz I have still said "researcher P thought abc....."

I see.... thanks for that reply Sneaks. I guess you're right, and it sounds more logical to be consistent, rather than accurate in this case (just in case it ruins the flow). In my thesis those words/names wouldn't work in terminology, but perhaps I could put a footnote at the word's first occurrence in the thesis. So from that point on the reader becomes aware. Or would that be a bit silly?

I think you don't need to point out if it's just a spelling difference. If they use two different words for the same thing then yes. You should use the same spelling through your thesis if you don't use quotes.
Fetishism is the common form and British spelling - Oxford Dictionary just gives this form.

thank you Blue