Sherwood was so good the tension gave you a stomach ache. And yet …

A few months from now, publications will start listing the best TV shows of the year. You don’t have to be a psychic to know that Sherwood is going to be around the very top of those lists. In an age in which prestige TV is rapidly giving way to simplified second-screen storytelling and mercenary intellectual property extensions, James Graham’s BBC crime drama stood out as a work of incredibly high quality.

It was urgent and timely, marrying a bigger state of the nation address to gut-wrenching character work. The cast was peerless, the score by 14th Street Music was atmospheric and doomy. All the new episodes were directed by Clio Barnard , for crying out loud. That’s about as good as television gets. There were moments during these last six episodes when you couldn’t help but watch through the cracks in your fingers, such was the gnawing sense of dread. Truly, you will see few shows as good this year.

However, because this was the second series of Sherwood, it is for ever destined to be compared with the first. And the problem is that, while the second series was very, very, very good, the first was perfect.

The difference between the first Sherwood and the second reminds me a little of Broadchurch, although the drop in quality was nowhere near as pronounced. Again, that was a show with a perfect first series. Like Sherwood, Broadchurch united a community around a horrible tragedy that pulled and tore at old bonds, and the final twist managed not only to tie the series together thematically, but also to obliterate the life of one of the main characters. So when the second series tried to start all over again with a new crime to be solved, the overwhelming feeling was: “So what?”

There was the tiniest element of this with Sherwood. The big reveal last time around was that local crime family matriarch Daphne Sparrow was secretly the spy cop who had been sent to the community during the miners’ strikes of the 1980s. Graham constructed the reveal perfectly, with episode after episode of hints and red herrings finally followed by a flashback episode that hit like a hammer. This reveal became the gravitational pull of the entire series, the element that elevated Sherwood from being a great show to being a classic.

It is also what left series two in a bind. Should Graham try to emulate the twist, or move on without one? In retrospect, it looks a little as if he tried both. The addition of Robert Lindsay to the cast, as a billionaire magnate with a previous life as a sort of ultra-spy cop, felt like an attempt to redo the Daphne reveal. But it was far less successful, partly because Lindsay’s character owned up to it early on, but mainly because he existed on the periphery of the main story. He wasn’t interesting enough to keep our attention. Look how early in the finale his story was wrapped up. Even the show knew that he was a sideshow.

Much better was the focus on the warring families. Sherwood has always been very good at showing the growing ripples of violence, how revenge takes on its own momentum and eats everything in its path. This was done extraordinarily well in series two. The bravura 20-minute sequence in the second episode, in which the rotten Bransons tracked down and killed the Bottomley family, was a feat of lurching dread. The entire series was speckled with moments like these, of tension so pronounced that it left you with a stomach ache.

But this focus came at the expense of leaving a few stray threads. Namely, what to do with Lesley Manville. The focus of the first series, she was left twisting in the wind a little in the second. Too big a name to ditch, but without any real story left to build on, her character became something of a narrative orphan. She was ultimately reduced to a love interest, which seems like a colossal waste.

On the whole, these are quibbles. When the time comes to look back on the year, Sherwood is still going to tower above most of the competition. But there is a sense that it has completed its task now. Unless Graham has a whopper up his sleeve, it feels like all the good stories have been hoovered up. Better to go out on top than succumb to diminishing returns.