Michael O’Leary, Ryanair’s boss, has turned into one of EU biggest defenders and his company has launched a special Brexit sale to prove it.

Ryanair said it will fly British expats home for cheap to boost remain votes in the EU referendum. The budget airline is offering flights to the UK from just €19.99 (£15.49) on Wed 22 June and Thur 23 June, polling day.

The special fares, only available until midnight on Thursday, are designed to help the more than 1.2 million British expats abroad to fly back to vote.

Kenny Jacobs, Ryanair’ chief Marketing Officer said Ryanair is a committed supporter of the UK remaining in Europe.

“Ryanair is absolutely clear that the UK economy and its future growth prospects are stronger as a member of the European Union than they are outside of the EU and with just 5 weeks to go, we will continue to work hard to help deliver a resounding ‘Remain’ vote on 23rd June,” Jacobs said.

The company is supporting the promotion of the “Remain” campaign, and O’Leary appeared in London on Monday alongside Chancellor of the Exchequer George Osborne to promote the case for staying in the EU on Monday.

“I despise much of the regulation that come out of Europe that add to consumer costs,” O’Leary said at a Bloomberg forum. “But there are sensible arguments for staying in, there are very few sensible arguments for leaving. ”

The Brexit camp has criticised O’Leary as he described the European Commission as an “evil empire” back in 2004.

But O’Leary is not the only one saying that a Brexit would be bad for business.

Microsoft and Hewlett Packard were the latest companies to push for UK to stay part of Europe.

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While Britain’s unicorns Zoopla, Just Eat, Ve, TransferWise and Funding Circle said this week they are in favour of a vote to remain in the EU next month.

George Osborne, who is pro-EU, has also warned that a vote to leave the EU would cause a “significant shock” to the housing market.