When will they stop talking over the music?

Mad Men's closing songs are being ruined by promos

Vintage telly: Elisabeth Moss and Kevin Rahm in 'Mad Men' (AP)

So how's Season 6 of Mad Men been for you? Too morbid, too boring, too Don Draper-focused or too crazy (take a bow, the tap-dancing Ken Cosgrove)? Apart from the over-emphasis on Don, it's none of the above for me. My only grumble concerns Sky Atlantic's intrusion into the end credits. What, really… the end credits? Yes, those – because no show on TV comes near to taking such care in selecting a closing song – and the channel has been interrupting it with its promos for other Sky shows.

It's a practice – variously called "squeezed credits" or, more topically, "credit crunch" – that's aimed at dissuading viewers from channel hopping, and it began in the States in the 1990s before coming here. "It's slightly insulting to the viewer, because they (the broadcasters) are obviously deeply paranoid that as soon as the drama finishes people go and make the tea or switch channels," says Downton Abbey composer John Lunn, who has also written the music for BBC1's The White Queen. "It's particularly bad for Mad Men because it's such a massive part of the drama what they choose to finish it with. It completely ruins it."

Creator Matthew Weiner, who cares so much about his outros that he persuaded Mad Men makers AMC to fork out $250,000 to use The Beatles' "Tomorrow Never Knows", is an obsessive collector of pop songs. And Weiner's choice of closing ditty is as eagerly anticipated by Mad Men fans as the latest twist in Peggy's love-life or whether Pete Campbell is ever going to turn on, tune in and drop out.

So far this season these have ranged from Chopin to Elvis Presley, Bing Crosby to Janis Joplin and Burt Bacharach to The Mamas & The Papas, by way of the psychedelic "The Friends I Haven't Met Yet" by Blue Sandelwood Soap, and "Reach out of the Darkness" by folk duo Friend & Lover. Actually, this last-named outro was the only song in the series so far not to be rudely interrupted by a promo – but only because Don and Megan's TV set was on in the background, with a news report about Robert Kennedy's assassination. Not that this was a sudden attack of sensitivity by Sky Atlantic, says Lunn.

"It's probably more because the other dialogue may get in the way of the other dialogue and they don't want that," he says. In fact broadcasters tend to use lyric-free outro music, thus escaping a clash when they gatecrash the closing credits. For the composers themselves, end credit music "is gone as a concept", says Lunn, who has been scoring television drama since the late 1980s. "I remember doing the incidental music for Auf Wiedersehen, Pet when it came back (in 2002) and Mark Knopfler did the end titles and he only agreed to do the end titles if there was no talking over it."

Sky needs to get it right with Mad Men, where the song has been specifically chosen to enhance or extend the mood of an episode, rather like that moment between dreaming and waking. "And it makes you think about what you've watched as well," says Lunn, a fan of the show who doesn't have to worry much about the way it's being televised. "I usually buy it on iTunes and watch it on my iPad," he says. "So I don't get that."

The final 'Mad Men' episode is on tomorrow at 10pm on Sky Atlantic