Are you considering european applicants? In the job description it's not clear, it says, if I have a VISA I can apply, but are you sponsoring the VISA?
Hey, same happened to me, but I just pinged the interviewer several times until he finally scheduled my interview. Now for the 2nd interview, I'm having the same problem. I guess they are quite busy :)
May I ask, if the company is in Eddinburgh, why are you looking for freelancers only in UK and not also in other european countries? I'm in Germany, only 1h difference.
Companies in the US still prefer hire remote workers in the states over europeans, I guess mostly due to the timezone, and because of the legal issues, it's always easier for them. You need to be an exceptional developer to overcome this disadvantage and make them they to consider to hire you.
Besides that, most of the positions posted in job boards are for Full-Stack or Front-End developers, not many Back-End or Data Science, which is what I am looking for.
If companies in Europe were more open to telecommuting, we would have much more chances to get a remote job and companies would have more chances to hire better developers. I guess this will change in the next years.