You can use the branch condition in the survey flow using Logic Based on GeoIP Location to filter the respondent using the IP address. Follow this link for more information.

Thank you - we've talked about that solution with our tech support team and they have suggested something we're going to try. Really appreciate your response.

I wanted to raise this issue again, because within the last three days, we have started receiving fake responses from outside the UK.
The restriction by location worked very effectively for a while but now it's not. Has something changed?
To be clear, these are people who are showing up on their response as being located in another country. They are not using a tool to hide their location. So for some reason this filter method isn't working any more. We have not edited the survey.
Can you help?

@krissf  Hi, I have the same issue as you. I want to know the location of the people from the country were is the study?

Did you find the solution? I used a branch if with GEeoIP Location but it didn’t work and also I enabled the Anonymize responses. 

Something else I didn’t find for this issue. Can you help me of someone from here, please?

Thanks

Sorry, I’m no longer working on the project and the Qualtrics experts resolve this somehow. We had huge problems with spam replies. Much sympathy if this is also happening to you.