I am a native Spanish speaker completing a PhD at Cambridge. I am planning to apply to MC and economic consulting firms with offices in London, Spain and Latin America. However, I am 34 and I have a noticeable accent. Since I would be competing against native speakers, I am not sure about my chances of being hired in the UK. Would you recommend me to apply to offices in London (and firms that work exclusively in the UK) or to be more realistic and apply only to offices in Spanish speaking countries? Thanks.

An accent will be no barrier whatsoever - unless you are completely incomprehensible. I imagine though that over the period of your PhD you will have managed to modulate any accent sufficiently to bring your spoken English up to an appropriate level and you are unlikely to be any worse off than people with for example broad Scots or Geordie accents.We are quite used to having our language widely used and at times abused and in London a huge proportion of people are non-native speakers; less so in this field than some others but still a significant number.So on those grounds, apply.Your age may prove more of an obstacle - as you will be aware people tend to leave education much younger in the UK and you may need to give some thought as to where you might fit.

I agree with DCFs comments regards accent. The only thing I would add is that in many instances it may be written English rather than spoken that is more important i.e. if you are quite research biased in your skill set then you maybe led down a research pathway within consulting (take someone like Wood Mac as an example). In this case your writing skills are extremely important so need to be to a high level.

I would do a mix. Some big players in Spain/South America as safeties. Some big players in the UK. And smaller firms will probably be only in the UK.

I don't think you should have a problem. In the UK, people are used to seeing and hearing English used and abused with a variety of accents, spellings and approaches to punctuation and grammar. The quality of written English in your post is perfectly fine. Admittedly, it is a very small sample but, if it is indicative of the general standard of your work, then you shouldn't have any problems. Your biggest challenge may be containing your frustration with clients who have poor English language skills despite being native speakers!