//Note that they do not have to stay in first country they arrive in.//
I agree that the 1951 convention does not say that a refugee must seek asylum in the first safe country they arrive in. But the implication of this phrase is clear:
“The Contracting States shall not impose penalties, on account of their illegal entry or presence, on refugees who, coming directly from a territory where their life or freedom was threatened in the sense of Article 1, enter or are present in their territory without authorization, provided they present themselves without delay to the authorities and show good cause for their illegal entry or presence.”
It implies that a person can be penalised for illegal entry if he does not arrive directly from a place where they are under threat. People in France are not under threat. The purpose of the asylum system is to provide succour to those fleeing places where their lives are in danger. It is not to provide a route to circumvent the normal immigration processes. This is exactly what those arriving from France are doing. People wanting to legally settle in the UK (by formal channels) have to participate in a process which takes some time an effort. People arriving rubber boats do not.
//NJ, if you look at part 2 in this document from the House of Commons Library, you'll see that isn't the case.//
The government's strategy is based on our own Immigration & Asylum Act:
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31. Defences based on Article 31(1) of the Refugee Convention.
(1) It is a defence for a refugee charged with an offence to which this section applies to show that, having come to the United Kingdom directly from a country where his life or freedom was threatened (within the meaning of the Refugee Convention), he—
(a) presented himself to the authorities in the United Kingdom without delay;
(b) showed good cause for his illegal entry or presence; and
(c) made a claim for asylum as soon as was reasonably practicable after his arrival in the United Kingdom.
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It would be interesting to learn how any of those arriving from France can comply with (b).
If you look further into part 2 you will find the UK’s views:
“Controlled resettlement via safe and legal routes is the best way
to protect refugees and disrupt the organised crime groups that
exploit migrants and refugees. We support these principles by:
• treating asylum claims made in the UK as inadmissible if the
claimants have suitable protection in another safe country
from where they would not face refoulement (that is, the
country would not force the claimant to return to another
country where they would be at risk of harm or persecution)
• treating asylum claims made in the UK as inadmissible if the
claimant has travelled through or has a connection to another safe country which is not their own, on the basis that the claimant has, or could have lodged their asylum claim there
• progressing to removal stage those who undertake illegal
journeys and subvert immigration control, to demonstrate
that such action will not lead to entry to, or settlement in
the UK."
That is quite clear and unambiguous. But the final part of that strategy falls apart because those arriving who would be denied asylum on the basis of the above are not processed rapidly and ejected. For those arriving from France that should take a matter of minutes. Instead they are accommodated and they eventually disappear into the ether. The overwhelming majority (I would put it at 100%) of those arriving from France would fail to be granted asylum under the UK government's own guidance but many of them are not removed because of institutional inertia. The only was to get round that is to prevent them from landing in the first place.