I showed them the picture of the guy in blue, and asked his age. They said '40s'
Do you mean the guy in the long sleeve pale blue top (I can;t see anyone else wearing blue)?
I certainly don't think he looks in his 40's
OP thinks of the 15 only 3 look in their teens. But there aren't all 15 teens in that picture only about 9 by my reckoning so all 15 are not photographed and there is at least one teen who is photographed several times looking older from some angles and obviously younger in other angles.
I despair that people (including me) are spending so much time being up in arms about 15 young men 15 who have family already in the UK and have sufficient evidence that the Home office are prepared to accept their age and have allowed them to join their family.
The Home office are not push overs, they are institutionally predisposed to resist taking anyone at all (hence our dreadful record with the Dublin Agreement). These young men will also be held pending further safeguarding checks.
Cases of "men" claiming to be boys in this country are more often people who have already got into the country who are claiming to be children not people whom the government has checked in advance.
There are potentially 150 children in Calais with ties to the UK - we are obliged to take them if they can prove they are children. It's hardly a flood.