What would you do with the immigrants that are not from persecuted countries and how would you qualify them?
Process their applications for asylum in the UK from whichever country they are in. If they meet the criteria, great, come on in. If they don't, then they have to apply elsewhere.
We have chosen not to have a process for remote application, because apparently having thousands of people risking their lives on boats and keeping them in processing centres at our expense is preferable.
I'm not sure about you, but I'd rather a system where people could be processed without having to pay criminals thousands to jump on a boat, and were able to work and contribute from the moment they arrive.