The case for the Remain campaign has dominated the Brexit debate in travel, led by the likes of easyJet chief executive Carolyn McCall who has argued EU membership is “vital to airlines and passengers”.

McCall appeared with David Cameron last month when he said a Leave vote would “put £230 on your family holiday”. A member of Cameron’s Business Advisory Group, McCall wrote earlier: “The EU gave airlines the freedom to fly across the Continent. That led to the dramatic fall in fares.”

That argument was backed by Ryanair boss Michael O’Leary who urged passengers to vote ‘Yes’ to Europe, despite saying in February: “I don’t believe leaving the EU will cause air fares to rise.”

Monarch Group chief executive Andrew Swaffield also lent strong support, asking: “Will the EU and its member states want to make it easy for the UK to keep the advantages of membership without being a member? At the very least we’ll have several years of tough negotiations and no seat at the table.”

The bosses of Heathrow, Gatwick and Manchester airports also called for the UK to stay in the EU, while Virgin chairman Richard Branson argued leaving would be “very damaging”.

There is little doubt senior aviation figures support staying in the EU, although most have refrained from comment.

For example, Willie Walsh, chief executive of British Airways’ parent IAG, has no ‘official’ view. IAG confirmed: “Willie Walsh’s personal view is that the UK should remain in the EU, although the EU needs reform.” However, Walsh told analysts: “Should there be a vote [to leave] we don’t believe it will have a material impact on our business.”

Other leading figures have contradicted the arguments for Remain.

Asked about the impact of a leave vote, Iata director general Tony Tyler said this month: “The European Common Aviation Area [ECAA] is already wider than the EU and includes non-EU member states such as Norway and Iceland. One plausible outcome is that Britain would remain within the Common Aviation Area, in which case nothing much would change.”

A Monarch spokesman disputed that, telling Travel Weekly: “The UK is not automatically a member of the ECAA so would need to negotiate full entry.”

Yet Lufthansa chief executive Carsten Spohr also downplayed the impact, telling Travel Weekly a Brexit “would slow down European trade, but would affect aviation less than other industries”.