Canadian authorities introduced a new requirement for Britons to apply for an electronic travel authorisation (eTA) before flying to the country in March but could not make it compulsory after glitches affected the online application forms, the Telegraph reports.

The leniency period ended this month, meaning anyone from the UK wishing to enter Canada by air must now buy an eTA for CAN$7.

The Canadian government this week issued a reminder to visitors: “The eTa requirement allows Canada to check that travellers are admissible before they board their flight, preventing those who are inadmissible from travelling to Canada in the first place.”

Those who arrive by land or sea - on a cruise ship, for example - are exempt from the scheme.

Travellers are required to fill out personal and health details, in a similar fashion to the Esta required for travel to the US. The eTA is valid for five years, or until the passenger’s passport expires.

The new eTA system has given Canadian officials the chance to introduce a third gender option for applicants. Those filling in the forms will be able to choose between male, female and other.