In reply to girlymonkey:
Aye, I get what you mean but you'll only ever catch symptomatic people with any border checks hence why so many worksites, vessels, offshore facilities have relied on health screening using temperature checks and declarations to limit those coming onsite. You're better to catch who you can then no-one at all.
Even NHS testing has a 20% return rate of false negatives. Only way to be sure would be quarantine everyone for 14 days (totally unpractical on an open border with people needing to travel either way for work) or you do what you can with screening. If someone chooses to lie about having symptoms, or exposure there's virtually nothing you can do given they're also the ones likely to ignore requests to self isolate / quarantine.
Any kind of control for internally in the UK would have to be best endeavors to limit (you'll never eliminate) transmission between areas. It;ll be interesting to see how the handle the localised outbreaks happening now down south.
We have had a fair amount of success on both our onshore and offshore sites - 0 infections despite working throughout the pandemic so far and moving personnel from all over the UK (knowing they would be checked a few people have dropped off crew changes etc if not feeling well). You might not catch every case, but you can still catch a lot which might be enough to keep it in check (if even needed). I could see ferry routes going the same way if infections start spiking on the mainland but not in the isles.
Cheers!
Stu