How about this: https://www.containcovid-pan.eu/? Choice quote: Given open borders within Europe, a single country alone cannot keep the number of COVID-19 cases low
Let's reverse the burden of evidence, and request [citation needed] for your implicit claim that the open borders lobby is not relevant here?
> time period during which the UK would've had to do this for it to be effective
.. lies roughly from Feburary to the present day. No reason to allow travel from countries with significant prevalence.
> all the right-thinking people were insisting that border restrictions were counterproductive, xenophobic and made things worse
[citation needed]