British Government foreign policy is often (if not always) based on a crude behavioral psychology which aims to apply negative reinforcement (punishment in common parlance) to unwanted behavior.
The shameful situation at Calais is an example of the punitive approach, as is the failure to honour promises to help children in Calais. It is a neglectful, lazy and anti-humanitarian stance. It is also irrational, because for the punitive approach to work, the UK Government should supply information to people in sending countries stating that they are putting themselves at risk by taking the journey, a 1% risk of drowning, of frustration and virtual imprisonment at places like the Jungle, and that it seems that half the British people and 3/4 of the British Press is now anti-immigrant.
That at least would be the truth, and would be informing would-be migrants of what they are letting themselves in for. Without this information, the suffering caused by the behavioural policy has no impact on the motivation of the next wave of migrants.
The laziness and incompetence of the Government is shown by the fact that there has been no real effort to "process" Jungle inmates: they are only now taking responsibility for children, and beginning to question and filter people.
The policy has been to render migrants at Calais non-people, with no rights, no future, no use, no humanity. They just exist, to be abused by anyone who wishes: police, right wing commentators, criminals, paedophiles. They are in limbo.
Humanity says : take them in, children first. Establish their claims to asylum. Tell them they are entering a country where homophobia, child marriage, and FGM is illegal. If necessary, do intensive vetting to screen out covert terrorists.
Above all, address the causes of migration, that is, war, poverty, human rights abuses and environmental degradation at the highest level and with real political will.
That is how a real, fit for purpose Government should approach the Calais problem,