:How is it unambiguous?  It seems like you're unaware of the other uses of the word constituency.  It wouldn't surprise me if the usage of "constiuency" to describe "a group of constituents" hasn't crept into Commonwealth English like it has in American English, precisely because in Commonwealth English the word refers to electoral districts. This isn't the case across the pond: Dictionary.com, for instance, gives these definitions for constituency:  
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 ## The body of voters or the residents of a district represented by an elected legislator or official. 
 ## The district so represented. 
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 ## A group of supporters or patrons. 
 ## A group served by an organization or institution; a clientele: The magazine changed its format to appeal to a broader constituency. 
 :It seems like only the second definition refers to electoral districts.  By the first, third, and fourth definitions listed constituency could refer to something else that's deserving of an article.