Latest: read our 'world first' review of Cathay Pacific premium economy

Cathay Pacific will upgrade selected Boeing 747-400s with both its all-new premium economy cabin and redesigned long-haul economy class seat.

A spokesperson for the Hong Kong flag-carrier confirmed to Australian Business Traveller that its first four-class 747-400 will first appear on the Hong Kong-London route on May  1st as CX255/252, running three days per week, increasing to daily from July 1st.

According to seating charts lodged in the booking system used by travel agents (and quickly reported by the AirlineRoute website), Cathay's four-class Boeing 747-400 will sport nine first-class seats, 46 in business class (split over the lower and upper decks), 26 in premium economy and 278 in economy.

The first and business sections remain the same as CX's current three-class 747, with the new premium economy cabin sitting between business and the slightly smaller economy section (which drops from the current swath of 324 seats).

Not only will the rejigged jumbo sport Cathay Pacific's highly-anticipated premium economy service – which CX exec Alex McGowan described to Australian Business Traveller as "an economy plus product, not a ‘business class minus’ product" – it will also see the Cathay's oft-criticised 'fixed shell' economy seats swapped out for the new long-haul economy recliners.

"Yes, it will also feature the new Economy Class seat" a Cathay Pacific spokesperson confirmed to Australian Business Traveller.

Cathay had previously announced both the premium economy and new economy seats would be fitted to Cathay's Airbus A330s and Boeing 777s, making their worldwide debut in March with flights to Sydney, Singapore, New York, Toronto and Vancouver.

In addition to the HK-London Boeing 747 service, the daily CX251/250 flights on the same route will be operated by a Boeing 777-300ER with Premium Economy "on a daily basis from from September 2012", the spokesperson said.

With a 38 inch pitch, 19.3 inch seat width and an 8 inch recline, each premium economy seat will have a large meal table and cocktail table, a footrest, a 10.6-inch personal television, in-seat power outlet, a multi-port connector for personal devices, extra personal stowage space, plus noise-cancelling headphones.

The new economy seats will have a six inch recline (two inches over the current long-haul economy seat) with extra storage space for personal items, a touch-screen video panel, an iPod/iPhone outlet to pipe your own music or videos through the in-flight entertainment system and a USB socket for powering and recharging devices.

For more details, read our report on CX's new premium economy and economy seats.

Cathay has previously ruled out an extensive refit of the 747s to add its new business class seats, however, given that the jumbos will be phased out by Boeing 777-300ERs.