On 14 June 2016, just over a week before the EU referendum, Vote Leave were keen to calm the fears of British scientists, farmers and others who relied on European funds. The thirteen Vote Leave ministers signed a pledge, still standing on Vote Leave’s website, that “If the public votes to leave on 23 June, we will continue to fund EU programmes in the UK until 2020.” One of those thirteen signatories was Dominic Raab.

How ironic then, that one of the first things Dominic Raab did as the newly-appointed Brexit Secretary was to suggest, on 21 July 2018, that the UK might not honour the hard-wrangled withdrawal agreement that guarantees continued funding of EU programmes until 2020.

Scientists for EU immediately called out Raab’s statement. We highlighted that this was effectively an instruction for UK scientists to stop writing Horizon 2020 grant applications. UK researchers could no longer be sure that any grant proposals submitted now would be eligible for support in seven months’ time, if our relationship with EU programmes was not secure.

A government statement released three days later sought to address these fears, “guaranteeing funding in event of a no deal for UK organisations which bid directly to the European Commission so that they can continue competing for, and securing, funding until the end of 2020.” On 10 August, a follow-up document said that in the event of a no-deal Brexit, the UK would still have access to Horizon 2020 as a “third country”. Finally, on 23 August, the government released its first batch of technical notes on no-deal Brexit.

This stated explicitly that, as a third country, UK institutions would no longer be eligible for three Horizon 2020 funding lines: European Research Council (ERC) grants, Marie Skłodowska-Curie actions (MSCA), and SME instrument (SMEi) grants for small innovative businesses.

That is a huge blow. We immediately calculated that these three lines represent 45% of the UK’s receipts to date from Horizon 2020. If the UK is currently winning €1.283bn each year from Horizon 2020, then a no-deal Brexit will cost UK research €577.35m (£520.7m) a year in lost opportunity to access these high-value grants.

By far the most critical of those funding lines is the ERC. The UK has won €4.73bn to date from Horizon 2020 overall, with €1.29bn of that in the form of ERC grants, €0.7bn in the form of MSCA grants and €0.14bn in SME Instrument grants. The ERC typically awards grants of €1-2m for talent from anywhere in the world to undertake pioneering research in EU and associated countries, and to build a team around them. Although the ERC awards are just over 10 years old, recipients have won six Nobel prizes, four Fields medals and five Wolf prizes. One in 14 publications from ERC projects rank in the top 1% most cited worldwide.

Even if the UK government was to compensate our research community for the financial loss of ERC grants, it would take far longer than the few months left until Brexit Day to build a fund as prestigious and attractive to global talent as the ERC. Our universities collect ERC grants like gold stars. To date, the UK has won 860 ERC grants – more than any other country. We now face the prospect of a UK drought for up to two years, and the loss of approximately 500 grants.

There are further frustrations with no-deal Brexit. As participants from a third country, UK researchers would be reimbursed by our government, not the European Commission. So UK Research & Innovation (UKRI) will shortly be registering all UK Horizon 2020 awardees so that it can take over payments if a no-deal Brexit hits. This gets particularly messy for UK project coordinators who currently receive funds from the EC and distribute them to project participants in other countries. The UK government will have to pay our coordinators and all partners, or the UK partner will have to step aside from any coordinating role.

This delivers a further blow. The UK government has said its future underwriting of UK participation applies only to UK entities and not their partners. This effectively means that in a no-deal Brexit, the UK can no longer coordinate multinational Horizon 2020 projects. The European Commission won’t pay. The UK government says that it won’t pay. Checkmate.

The UK has coordinated more Horizon 2020 projects than any other country to date, and has a hard-earned reputation for effective project leadership. In a no-deal Brexit, this leadership role is stone cold dead. That prospect is impacting projects being prepared right now.

Breaking the withdrawal agreement with the EU27 not only undermines our relationship with our European neighbours, it is also a direct betrayal of British scientists. No deal is simply not an option.

Dr Mike Galsworthy (@mikegalsworthy) is co-founder & director of Scientists for EU (@scientists4EU)