Explaining the appeal of Downton Abbey isn't actually as easy as it may sound. The show plays by a different set of rules than its fellow dramas and that's a large part of why it works. Sunday night, the show wraps its fourth season stateside and has continued to put up strong numbers.

(Credit: iTV/PBS)

Split schedule

U.K. series by nature are vastly different from those produced here in the U.S. Differences in humor (or "humour") and storylines aside, most U.K. programs don't have the traditional seven-year run of 20+ episodes a season. In many cases, the program runs between three and eight episodes and then they call it a series. Sometimes they come back and sometimes they don't, which ironically makes Downton the exception to the exception.

The show runs for eight episodes, plus a two-hour-long season-ender that airs on Christmas (in the U.K.). It's used that formula for three of its four years and it works. It also premieres in September, like most of our domestic programs do, but audiences on the other side of the pond get it first on British broadcaster iTV (ITV -0.56%), before it's aired stateside on PBS.

Abbey awareness

(Credit: iTV/PBS)

Now you'd think a four-month delay could have a negative impact on Downton's appeal and its ratings, but it's actually quite the opposite. The delay raises the awareness here in the States, and that was never clearer than at the start of this season back on Jan. 5 when the premiere hit towering record numbers. Initial ratings came in at 10.2 million viewers, a 22% season-to-season jump.

Combining on-air views, streaming views, and DVR replays, the episode eventually was estimated to have reached more than 15 million people ... topping the numbers of some of today's top U.S.-produced dramas. Downton also held its own against the Super Bowl, pulling in 6.8 million viewers, a 200,000 increase from its performance last season against the big game.

The show's massive fanbase also transfers over to the awards race. Downton original competed at the Emmys in the (then-combined) Made-for-TV movie or Mini-Series race, in which it won top prize. The next year it switched over to the Drama category, which may have seemed liked a risky move, but it was one that paid off. The second season snagged 16 total nominations, five more than its first year, though it only won half as many of the categories. Despite that number falling even lower in season three, it still earned 12 nominations and now seems like a yearly lock for at least a Best Drama nomination, which is a major accomplishment and something any other series would gladly take.

Competition

The Downton effect is also unique as it only airs two months out of the year in the U.S., which means it doesn't cross paths with a number of shows that have traditionally owned Sunday nights. HBO for instance, hasn't had a real January/February drama staple in years. And while Showtime has built a potent lineup of its own on that night, the two seem to not really affect the other.

The real problem Downton presents to its rivals is its cultural impact. This is a quality show with quality performances and all aired in a short period of time. Because there's no danger of it being held off the air for weeks at a time, or even worse, suddenly being cancelled, it is an appealing alternative to traditional U.S. programming.

Unlike shows that have to produce between 13 and 24 episodes a year, there's also no room for filler. Audiences feel safe tuning in as they know they aren't getting strung along. More importantly, they know when the time comes to wrap, they'll get a proper ending.

The King of Downton

(Credit: Andrew Crowley/Daily Telegraph)

Most of the credit rests with series creator Julian Fellows, who also writes every episode of the show. Last year, though, Fellows signed a deal with NBC for a new series called The Gilded Age, which will be his next project. For now Age is in a state of limbo until Fellows works out things on Downton. While he's hinted he could turn his show over to a group of writers in the future, he's also suggested he may just as easily set an endpoint.

After all, going back to the exceptions mentioned earlier, key members of the show's large ensemble have already asked off with a handful more expected to bow out in the not too distant future. U.K. actors don't sign the same long-term contracts American actors do, as they like being free to go project to project. Of course that make things complicated for a series that has gathered this much international appeal.

No matter when the gates of Downton shutter for good, the series has made its mark on popular culture and showed other networks there's a successful alternative business model they should pay attention to ... especially before another rival cashes in.