When I search for "football images" on google.co.uk, it knows that I mean the sport that elsewhere might be called "soccer". If I do the same search on google.com, I get American Football.
I'm using the custom search API - how can I tell it that I'm in the UK and would like results relevant to here?
Sorry, I ended up answering this myself. I couldn't get any of the instructions under the custom search API itself to work (although the answer offered above was also mentioned there, but this just made my CSE Context XML apparently invalid), but you can make requests to a custom search engine by using the instructions here https://developers.google.com/custom-search/json-api/v1/using_rest and an API key.