The British Society for Immunology have also wrote an open letter of concern. They are immunologists and know about immunity.
Yes, not everybody signing is a specialist in epidemiology, but so what? The point is that a good number are -- there is no clear consensus among UK experts for the UK government's position. And among global experts, there is a clear consensus against their position.
Well there is a huge government drive to portray that this is the case right now.
Whenever that happens, it always arouses suspicion that something is not quite right.
As a group, it's hard to imagine that UK experts in Epidemiology and related fields deviates significantly from their peers globally.
On a more serious note, petitions and other methods by experts to publicly state a position isn't just about influencing government policy. It's also a political tool in the aftermath of failed policy. Just like the current panel of experts is a political tool employed by the government to justify the biases in its policy.