The group’s financial modelling estimates the scheme could cost £270.9m over a 23-month operating period.
It says this could equate to between £443 and £853 per occupied bed per night, compared with a hotel benchmark of £144.98.
However, the campaigners acknowledge that their calculations are estimates rather than official Home Office costings.
The letter also highlights a National Audit Office investigation published in March 2024, which found the government’s early programme of large asylum accommodation sites was expected to cost £46m more than hotels, despite originally being intended to deliver savings.
The report also identified £2.9m in fruitless expenditure on the previous, abandoned proposal to use RAF Linton-on-Ouse as an asylum centre in 2022.
Campaigners say any new business case should include the full cost of infrastructure improvements, security, healthcare, policing, transport, emergency services and eventually restoring the site.
They say: “Can potentially hundreds of millions of pounds of public expenditure be justified for a temporary facility with such a limited useful life?
“If the Home Office cannot demonstrate that the proposed Linton asylum centre represents sound value for money, the government should shelve the proposal and pursue a more financially responsible alternative.”
In response, a Home Office spokesperson said: “The government is closing every asylum hotel, saving taxpayers over £1bn on asylum support since the election.
“We are working to fairly house asylum seekers across the country, moving asylum seekers into alternative accommodation, including former military sites which are designed to be self-contained to reduce impact on the local community.
“As part of the process, we engage with local authorities and police forces to ensure the safety and security of those in the surrounding area.”
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