The much-vaunted first scheduled non-stop service between the UK and Australia is "exceeding expectations" in terms of sales, Qantas has told Telegraph Travel.

The Heathrow-Perth route launched in March to great fanfare, with Qantas fulfilling a decades-long ambition to run direct flights between Australia and the UK. The 8,991-mile service entered the record books as the second longest flight in the world and first ever non-stop passenger link between the two countries.

According to data released by the Civil Aviation Authority (CAA), the UK aviation governing body, the flights have been departing only 78.1 per cent full, on average, since the route was launched - meaning dozens of empty seats.

But the CAA recording of passenger numbers travelling between British and overseas airports, from which Telegraph Travel was able to identify the number of travellers flying point to point between London and Perth, does not take into account the passengers using the flight to connect onto either Melbourne or Sydney, or onward travel in the other direction.

A spokesperson for Qantas would not comment on load factors but said: “Our London-Perth route is performing well - it is definitely exceeding our expectations.”

The CAA datas shows that over the whole of April - afrer the service launched in late March - 10,692 passengers flew to or from Perth. As Qantas is operating a daily flight in each direction, using a Boeing 787 Dreamliner capable of carrying 236 passengers, its monthly capacity totals 14,160 seats, meaning that in April 75.5 per cent of the potential maximum flew direct between London and Perth with no further onward travel.

In May, this figure rose to 76.2 per cent and increased again in June, the most recent month for which figures are available, to 83.7 per cent. It is not possible from the data to tell how many passengers began or ended their journey in Melbourne or Sydney or airports beyond London.

Passenger load factor is a key measure in a route's performance as every empty seat is lost revenue. Qantas is expected to reveal more about how its record-breaking flight is faring next week when it announces its latest financial results.

Qantas says its route has exceeded expectations Credit: aluxum/Monkeys

The Perth-only figures would suggest that the flight is performing better than the airline's overal average, which for 2017 was 80.6 per cent. The global average load factor across all carriers last year was 81.4 per cent.

In the run-up to the flight’s launch there was speculation that the 787 used on the routes - flight numbers QF9 and QF10 - could not be flown at full capacity as the total weight would jeopardise fuel efficiency. Qantas CEO Alan Joyce has said previously that each of the cabins in the Dreamliner would have “a very high level of comfort... and a lower seat count that most of our competitors”.

This week the Perth-bound leg set a new time record, arriving in Australia after just 16 hours and 23 minutes rather than the 17 hours and 20 minutes scheduled. The rapid journey time, aided by reduced head winds, should help Qantas save money on fuel.

The shorter flight could also help boost passenger enthusiasm, though travel agents have been reporting strong sales despite the long journey time.

A spokesperson for the tour operator Trailfinders said bookings between now and the end of the March showed the service was “proving very popular indeed [and] there is very little availability left at this stage”.

Qantas said demand for its business suites and premium economy seats has been “very strong, with consistently high loads in these premium cabins”, adding that the customer response to the Dreamliner aircraft has been “overwhelmingly positive”.

“It’s an aircraft people really enjoy flying on and we’ve seen a double-digit increase in our customer satisfaction scores,” the spokesperson said.

Qantas is planning further forays into the realm of ultra-long-haul travel, and recently announced “Project Sunrise”, with the airline challenging both Airbus and Boeing developing aircraft that can fly anywhere in the world from Down Under.