UPDATE | Thai Airways has backtracked on its decision to withdraw first class from Australia, with 'Royal First' flights to continue between Sydney and Bangkok.

TG471, 472, 475 and 476 were all to be downgraded to a Boeing 777 from October 26, although the airline has reinstated the Boeing 747 on its Australian flights.

Unlike the Boeing 747, Thai's Boeing 777s come without first class. Sydney is Thai Airways' only Australian Boeing 747 destination, with the jumbo's disappearance previously flagging an end to the airline's first class service to Down Under.

A Thai Airways spokesperson confirmed the shake-up to Australian Business Traveller, advising that first class will continue to be available on both of Thai's flights between Sydney and the Thailand capital.

First class fares are currently being withheld on TG475/476 from October 26, so if you're looking to travel in first class after that date, you'll need to patiently await their reappearance.

Flights between Perth and Bangkok will also get a rejig, with the Boeing 787 Dreamliner currently making an appearance from September 21 through to October 25 before the older Airbus A330 returns from October 26.

PREVIOUS | Thai Airways will remove first class from Australia-Bangkok flights in October this year as it trades in its iconic Boeing 747s for the smaller Boeing 777-300 on all Sydney flights.

As Thai's last remaining first class destination Down Under, downgrading to an aircraft type that comes without a first class cabin sees Thai's luxury travel wrapping up from October 26 2014.

That's when the three-times-weekly TG472/471 flights are being downsized between Sydney and Bangkok, along with the daily TG476/475 services between the same cities.

A Thai Airways spokesperson revealed to Australian Business Traveller that "this aircraft type is more efficient than the Boeing 747-400", and that "we are hoping that it will enable us to grow the frequency of the (TG472/471) flights through time."

Business class picks up a middle seat on the TG472/471 flights, which isn’t found in business on the airline’s Boeing 747 fleet.

The angle of the ‘sloping sleeper’ business class seats remains the same between the Boeing 747 and Boeing 777 aircraft, sitting at a near-flat 170 degrees.

A Thai Airways spokesperson could not yet advise which variant of the Boeing 777 will be used on the airline's daily TG476/475 run, although confirmed that Thai would no longer offer first class to Sydney – and thus, Australia.

If Sydneysiders luck out, Thai's newer Boeing 777-300ER aircraft come fitted with 180-degree fully-flat beds in business class – a 10-degree improvement over that found in business on the Boeing 747.

They're also the same seats as found in business class on the airline's Airbus A380 fleet, which Australian Business Traveller reviewed on the inaugural superjumbo flight.

While Thai doesn't fly its A380 to Australia, the Boeing 777-300ER has been appearing on flights to both Brisbane and Melbourne:

The aircraft schedule hasn't been finalised for Q2 2015, although Thai Airways' spokesperson had earlier told Australian Business Traveller that the airline "expects this flight to continue with the Boeing 777-300".

For flights through Q1 2015, the aircraft swap for TG472/471 is now reflected on the Thai Airways website, although the daily TG476/475 flights are yet to be rolled over.

Until that happens, first class fares on the affected flights have been withdrawn from the booking system, with passengers who have already booked to be re-accommodated in business class.

That's unfortunate news if you've already used Royal Orchid Plus miles to upgrade to first class, or have stocked up United miles to make a Thailand trek.

As a Thai Airways Sydney-Bangkok flight in first class can currently be nabbed for only 40,000 United miles under the revised MileagePlus redemption rates, it's a particularly great loss to travellers who purchase miles to redeem for heavily discounted travel.

The aircraft downgrade and all-out removal of first class to Sydney and Australia follows the move to pare back Thai's Sydney-Bangkok flights from 12 to 10 each week and Qantas' removal of the Boeing 747 from its Singapore flights.

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