Business travellers will have an extra Singapore Airlines connection to London's Heathrow Airport from September, as SQ adds a fourth daily flight from its Changi hub.

The airline's newest fully flat business class seats with direct aisle access for all passengers will be found on the Boeing 777-300ER planes that are planned for the route.

The new flights will start ramping up from the week of 9 September, when the SQ305/306 return will run four days a week.

From the week of 21 October, the flights will be daily -- although flight times will shift around slightly as the weekly schedule comes into force.

When the flights go daily, westbound flight SQ306 will be a 0045 departure from Singapore, arriving into London at 0655 the next morning.

Return flight SQ305 will leave London in at 1515, arriving in Singapore at 1155 the following day.

Speaking to Australian Business Traveller, a Singapore Airlines spokesperson was keen to spruik the new connections for Australians: "Sydney, Melbourne, Brisbane, Perth and Adelaide will each gain an additional seamless connection to London Heathrow as result of the introduction of the late evening service out of Singapore."

"Once the fourth daily service has taken full effect, all of Singapore Airlines ports in Australia will have the benefit of an added seamless connection to London Heathrow as well as increased travel options for our customers depending on their itineraries or any planned stopovers in Singapore," the spokesperson promised.