Those who do attempt the crossing are likely to speak English rather than French or have family members already in Britain.
Others may come from countries with historical ties to Britain or places where the military has been active, such as Afghanistan.
Britain’s benefit system is blamed for attracting migrants but the weekly allowance of £39.63 is less generous than in France, where asylum seekers get £43.50 per week and can start applying for work after six months.
But it is easier to find informal or black market jobs in the UK than in France or other EU countries.
What is France doing?
Britain has two recent deals, worth £28 million and £54m with France to pay for increased surveillance of the coast.
France has rejected UK demands for joint Border Force and French Navy patrols in the channel.
Since November’s £28 million deal, the French have stopped more than 18,000 attempted crossings but most still pass undetected under cover of night.
Despite making more than 10,000 arrests between from August last year until August 2021 and spending €217 million to stop the crossings, according to French Senate figures, the authorities have been largely unsuccessful in stopping the migrants.
Most of the boats leave the Northern coast of France. This is often the culmination of a long and dangerous journey in the hands of criminal people smugglers.