|Operated by||Arriva Shires & Essex|
|Garage||Harlow and Ware|
|Via|| Hertford |
|Length||92 miles (57km)|
|Frequency||Every 60 minutes, 120 on Sundays|
|Journey time|| 2 hours 12 mins - 3h 36m |
Varies with time of day
|Day||03:35 until 00:39|
|Night||No night service|
| † peak vehicle requirement|
See also: Green Line Coaches
Green Line route 724 is a high-profile limited-stop express bus service, currently operated by Arriva Shires & Essex as part of the large Green Line Coaches network. It operates between Harlow and Heathrow Airport, and is partly funded by the British Airports Authority (BAA). It is the only Green Line service to be operated by buses rather than coaches.
Route 724 was started in 1966, on a similar route to the current day service.
In 1998, a fleet of nine DAF SB220/Plaxton Prestige were purchased, with extra luggage space built in. These were some of the first low floor wheelchair accessible buses to operate in the United Kingdom.
These were replaced in August 2006 with a fleet of nine new Mercedes-Benz Citaro, an investment of £1.3 million. These were the result of a Quality Bus Partnership between Arriva, BAA and Hertfordshire County Council. These buses seat 39 and also have extra luggage racking. The previous DAFs were refurbished and cascaded around Arriva Shires and Essex, some now branded for route 500 (Watford - Aylesbury). 
The most recent development of the route reflects the opening of Heathrow Airport's new Terminal 5 in March 2008. Service 724 will run via Terminal 5 between the Central Bus Station and Terminal 4. 
- Green Line Coaches website
- Green Line - Route 724
- Arriva Shires & Essex website
- Full timetable - Arriva
- Full timetable - Transport for London