First, the glamour, joy and excitement of aviation evaporated. Now the cherished perks of travelling executives, frequent-flyer points, could go too.

On some trips from the UK, it now costs more in taxes, fees and charges to get a “free” flight than to buy a ticket on the open market.

Frequent flyers using accumulated miles to fly from London to Amsterdam and back could find the passenger in the next seat with an ordinary ticket has paid £11 less for the same trip.

Business travellers have long grumbled about the diminishing value of free tickets for loyal passengers.

Things have now reached a stage at which mileage can have a negative value.

Research reveals frequent travellers on Air France/KLM's Flying Blue scheme are charged £110 plus 20,000 miles for a Heathrow-Amsterdam round trip — available to buy for £99.

A KLM spokeswoman said the £110 plus 20,000 miles cost was “available to frequent travellers throughout the year, even at peak time”.

“[But] the £99 offer is much more restricted in availability,” she added.