"Take the National Express when your life's in a mess" goes the opening line to the cheery single. It continues: "On the National Express there's a jolly hostess/ Selling crisps and tea/ She'll provide you with drinks and theatrical winks..."
Last week, Hannon explained his affection for the company, saying: " `National Express' [the single's title] is an observation of life. There is every walk of life on these buses. And also it's a little light relief at the halfway point of the album."
The song, on the band's new album, Fin de Siecle, was being played last week at the announcement of the company's interim reports (profits up 43 per cent to pounds 34.4m for the first half of the year), and journalists were being offered free copies.
The single itself won't be released until mid-January, but National Express Ltd, the division of the company that runs the coach operation, is poised to take full advantage. "It's almost certain that we will be buying them for staff and promotion purposes," said Kevin Bennett, the director of marketing.
Given that more than 10,000 people are employed across the National Express Group, the tune - already receiving ample airplay on radio - will probably be widely whistled throughout Britain's coach depots.
"We are talking to the record label Setanta about how they would like to work with us on the video for the single and its packaging," says Mr Bennett. "The student market, which is vital for the music industry, is also important to National Express, so that's a great affinity for us.
"The lyrics are light-hearted, it's a catchy tune; and what with it being on the radio a lot at the moment it's very good for us, especially now as students are going back to college."
But the mass purchase of the single in January won't distort the charts, apparently. A spokesperson for the Chart Information Network, which compiles the charts, said: "The record label would inform us of this sort of occurrence. Also, the charts are calculated in the retail area, each barcode being registered as a single is sold. If anyone tries a mass buyout, we would spot the irregularities as a distortion of national sales patterns."
A number one hit normally has to sell many more copies than the 10,000 figure of National Express's workforce: typically a chart-topper sells between 70,000 and 160,000.
Pop history has a number of singles immortalising products and companies. Janis Joplin pleaded "Oh, Lord, won't you buy me a Mercedes-Benz?", Madonna did her "Vogue", and Catatonia cashed in on The X Files' popularity with "Mulder and Scully".
But such singles aren't without their legal wrangles: Aqua's "Barbie Girl" landed them in trouble with the manufacturers of the doll, and - most famously - The Kinks had to change their Coca-Cola line in "Lola" to "cherry cola" to avoid using the brand name.
In the case of National Express and The Divine Comedy, however, the song looks set to be mutually beneficial. As the lyrics say: "Don't just sit there feeling stressed/ Take a trip on the National Express."