BOBBLE hats on, Shetland (BBC1, Tuesday, 9pm) is back. Not that the hardy island souls featured in Scotland’s very own Nordic noir need such southern softy garb. Even in the depths of winter, I’ve seen DI Jimmy Perez nipping about without even a scarf. As for gloves, you’d have more chance of seeing him in a taffeta ballgown.

There was a raw wind blowing as the fourth series began. A local man, jailed for the murder of a teenager 23 years ago, had had his conviction overturned and was heading home. No one put out the bunting. With the evidence pointing to another suspect still at large, the islanders were on edge. Time for the calming presence of Perez (Douglas Henshall) to make itself felt.

Shetland stands out from the crowd because it is the polar opposite of a shouty police drama. Henshall sets the tone with his sorrowful, “Nobody knows the trouble I’ve seen” look, and his right-hand woman, DS “Tosh” McIntosh (Alison O’Donnell), has inherited the same mien. We were all worried about poor Tosh after the third series. While she is not out of the woods of depression yet, I’m pleased to report that she has withdrawn her transfer request.

Perez had competition for detective of the week from Collateral (BBC2, Monday, 9pm). Yet apart from both being crime dramas, the two were a universe apart. Collateral being a David Hare creation, his first series for TV, it was set in London, no expense had been spared, and coachloads of top drawer actors had turned out, some of them better cast than others.

Hare had gone to such lengths to avoid cliches in creating the character of DI Kip Glaspie (Carey Mulligan) that he ended up with someone scarcely believable. That the lead detective in the case of a murdered pizza delivery guy was awfully posh one could just about swallow. But an ex-champion pole vaulter? Why not go the whole hog and put her on roller skates? John Simm was similarly miscast as a painfully right-on Labour MP. “Look,” he said to a lover wisely dumping him, “if the Labour Party makes you angry, what do you think it does to me?” If it makes you say lines like that mate, I’d get out quick.

Breadline Kids (BBC1, Monday, 9pm) met some of the 260,000 Scots children living under the poverty line of £14 a day. The stories were as predictable as they were heartbreaking. Here were old heads on young shoulders, mums determined to make the best of a bad lot, and tears that broke through all the same. As this BBC Scotland documentary showed, jobs won’t lift people out of poverty if there are not enough decently paid posts to go around.

John Simm was on double bubble pay this week, first appearing in Collateral and then Trauma (ITV, Monday-Wednesday, 9pm). This three parter, shown over consecutive nights, came from the laptop of Mike Bartlett, aka the creator of the award-winning Doctor Foster. As such it was red hot. Not the laptop (although they can get a bit toasty after a while), but the dramatic property.

Simm played Dan Bowker, an ordinary working bloke cast into unimaginable grief by the fatal stabbing of his 15-year-old son. Convinced that fancy pants trauma surgeon Jon Allerton (Adrian Lester) had made a mistake in treating the lad, Dan set about trying to force him to tell the truth.

Trauma had all the flaws familiar to anyone who had ridden the rollercoaster of credibility that was Doctor Foster. The central premise, dad blames surgeon for son’s death rather than the killer, was shaky. But then other things started happening, such as Dan walking unchallenged into the operating theatre where his son was lying on the table.

As with Doctor Foster, Trauma was just about saved by a blistering pace and an A-list cast.

Damned (Channel 4, Wednesday, 10pm) was another example of telly that had you wondering if commissioning editors were from Mars and viewers from Venus. Certainly, the sitcom set in a social work department was topical and edgy. Sure, it had Jo Brand and Alan Davies on typically sarky form. But the whole thing was like a challenge to the notion that nothing is out of bounds for comedy. You would need a script of the utmost brilliance to get laughs out of a plot centring round a prostitute having her children taken into care, and I’ll be damned if this had one.

Life went on in Two Doors Down (BBC2, Monday, 10pm) despite Cathy and Colin falling victim to a break-in. “See if I get my hands on them,” said Colin (Jonathan Watson), puffing out his chest. “I can just see the headlines noo,” sighed Christine (Elaine C Smith). “MAN BORES BURGLAR TO DEATH”. As we say in these parts, ooft.