All depends on an individual’s situation. Apparently it’s possible to apply for a visit visa then claim asylum upon arrival. This of course requires that they retain their documentation versus coming here by dingy where it all gets destroyed en route. It may not be easy, but it’s safer and also legal.
Total Law…
“This means that while it is possible to claim asylum while on a tourist visa in the UK, it may be difficult to do so, and seeking legal representation can help your case. Otherwise, there may be some resistance and arguments against the case.
This being said, while these laws can be difficult, many individuals claim asylum in the UK each year, with successful asylum applicants making up over 70% of the decisions made by the Home Office in recent years.”