The civil servant in charge of the Home Office has said he does not have evidence to show the plan to send asylum seekers to Rwanda will act as a deterrent.
In a letter released at the weekend, Matthew Rycroft, the permanent secretary at the department, said that because the evidence was not available to justify the plan, he could not be sure it would provide value for money to the taxpayer.
The release of the letter coincided with Justin Welby, the archbishop of Canterbury, using his Easter sermon to say the principle behind the plan “cannot stand the judgment of God”.
The home secretary, Priti Patel, justified the Rwanda proposal on the grounds that the number of people crossing the Channel in small boats hoping to claim asylum in the UK has been rising sharply and that the prospect of being sent to Rwanda would act as a deterrent, disrupting the people-smuggling trade.
She also claimed the costs of the scheme would be a “drop in the ocean” compared with the long-term costs of allowing small-boat Channel crossings to continue to increase.
But in his letter Rycroft said he could not be sure this argument was correct.
He told Patel: “Value for money of the policy is dependent on it being effective as a deterrent. Evidence of a deterrent effect is highly uncertain and cannot be quantified with sufficient certainty to provide me with the necessary level of assurance over value for money.”
Rycroft wrote to tell Patel that she would need to issue a ministerial direction for the policy to go ahead. This is a rare procedure used when civil servants cannot justify a policy on sound public spending grounds and decide to flag up their concerns so that ministers have to take a formal, political decision to override them.
In his letter Rycroft stressed that he was not saying the policy would not work as a deterrent – just that it was impossible to know either way.
“I do not believe sufficient evidence can be obtained to demonstrate that the policy will have a deterrent effect significant enough to make the policy value for money,” he said. “This does not mean that [the policy] cannot have the appropriate deterrent effect; just that there is not sufficient evidence for me to conclude that it will.”
At the weekend the Home Office also released the text of Patel’s reply to Rycroft, in which she confirmed that she was issuing a ministerial direction.
She said the asylum system was already costing the government £1.5bn a year and, while she accepted it was not possible to accurately model the deterrent effect of the Rwanda policy, “we are confident this policy is our best chance at producing that effect”.
She also said it would be “imprudent … to allow the absence of quantifiable and dynamic modelling … to delay delivery of a policy that we believe will reduce illegal migration, save lives and ultimately break the business model of the smuggling gangs”.
Britain has promised to pay Rwanda an initial £120m to launch the scheme. It will also pay a sum for every person resettled in the country, although these figures have not been disclosed.
The Home Office is launching a £100,000 social media advertising campaigning telling potential asylum seekers, in their own languages, that the policy that could send them to Rwanda if they cross the Channel in a small boat is already in place.
In his sermon on Sunday, Welby said there were “serious ethical questions” about the proposal.
“The details are for politics and politicians. The principle must stand the judgment of God and it cannot,” he said.
“It cannot carry the weight of our national responsibility as a country formed by Christian values, because subcontracting out our responsibilities, even to a country that seeks to do well like Rwanda, is the opposite of the nature of God, who himself took responsibility for our failures.”
In response, the Conservative MP Andrew Bridgen accused Welby of “a little bit of naivety”, telling Sky News that he did not think the archbishop’s views were “in step with the views of the country”.
