I begin with a chuckle that turns into a lament. The Pickerskill Reports, the series in which a former public school master reminisces in a tone as lacerating as it is fond, is no more. Author and director Andrew McGibbon has declared it's a wrap with The Last Report, bringing bank-holiday merriment with its mix of the scholarly and the fantastical in a one-off special.

The series originally starred Ian Richardson, whose recruitment was a coup in itself and whose performance so matched the withering put-downs and acute insights of the script that all seemed lost for the show after his death in 2007.

Yet producer Curtains For Radio brought the series back in 2009 with another casting triumph - with his reedy-voiced enunciation and donnish demeanour, Ian McDiarmid stepped effortlessly into the other Ian's footsteps. This new play finds McDiarmid in full flight, relishing the effortless dialogue ("brandishing your braggadocio"), high-table erudition and gentle, literate comedy that can turn savage in a second.

As the 'progressive' head, Michael Feast fuses the sinister and the cynical, while Tony Gardner is the spluttering maths master Lefty, around whom Thomas Brodie-Sangster's precocious pupil, Porter, runs rings. With her girlish politeness, Elaine Cassidy is the antithesis of a villainess - until she is revealed to be working for the kind of suspect organisation beloved of 1960's TV series such as The Avengers.

Before Richardson's death, there was dangerous talk of a transfer to television, but perhaps The Pickerskill Reports is best remembered as one of radio's timeless jewels.

Radio Times review

Is now, or ever, the right time for a sitcom set among soldiers serving in Afghanistan? Bluestone 42 tested the question with its tales of a British army bomb-disposal unit.

Bluestone 42 is written by Richard Hurst and James Cary, who have both worked on Miranda and are experienced comedy technicians. They kept scenes to a minimum length, filled any gaps with gags, and efficiently established their characters and the central plotline of smooth captain Nick (Oliver Chris) chasing cute female padre Mary (Kelly Adams), who finds him attractive despite herself but constantly rebuffs him.

It was a bit too efficient. This was a fairly conservative workplace sitcom, hung on a talking point that was likely to get commissioning editors and journalists interested. There's no cause to doubt Hurst and Cary's research, or their interest in the subject matter. What is in question is whether the comedy and the subject matter meshed together in the right way.

The soldiers were comedy types: a fussy man, a tomboy, an exceptionally vulgar Scot, an omniscient boss (Tony Gardner) who pops up at inconvenient times. They schemed and joked with each other as the captain and the padre set a will-they-won't-they arc going. With Bluestone 42 unwilling to offer comment on the war itself, the driver for episode one's plot might as well have been a lost lever-arch file or someone scratching the MD's car.

In fact it was an American colonel (Mike McShane) being fatally shot in the head, the flip treatment of which might well have troubled you if you view Western soldiers in Afghanistan as making a grim but glorious sacrifice. But if you see them as oppressive occupiers, Bluestone 42 had that covered too. The Yank's death was softened in advance by his annoying habit of crowing endlessly about his tour of duty in Fallujah.

Fallujah. Fallujah. The word became a punchline. It's just one of those funny place names, isn't it? Like Penge, or Kidderminster. At least it might be for viewers who are a bit hazy on what happened to the locals there in 2004. Anyway, Nick the raffish captain sorted out all the palaver about the team being fired on by launching an RPG into the Afghans' hut, killing them all and letting us get back to the comedy.

Of course a sitcom in a warzone isn't off-limits. But Bluestone 42 shows that it's... a minefield.

"Too soon?" one character asks in ­Bluestone 42 after he makes a tasteless quip about the death of a CIA officer. That's the question you might be asking after watching BBC3's new sitcom about a bomb disposal team in Helmand Province. After all, it's usually polite to wait until a war is actually over before you start making jokes about it.

The Korean War had been done and dusted for more than 20 years before M*A*S*H waded in. The same goes for Dad's Army, while Blackadder Goes Forth waited a good 80 years for the dust from the First World War to settle.

And after the number of documentaries the BBC has made about Afghanistan - in particular Our War, also on BBC3 - the show's writers will have been acutely aware of the potential offence they could cause by making comedy out of conflict. It seems their main concern was getting all the military details right, rather than whether they should be making it at all.

But, putting all thoughts of whether Bluestone 42 is wildly inappropriate or not to one side, thank goodness that it's actually very funny, with an excellent line in banter.

Oliver Chris is perfectly cast as Captain Nick Medhurst - the officer who fancies himself a little too much as the dashing war hero, and expects the new female padre (Hustle's Kelly Adams) to feel the same.

The big ensemble cast also includes Tony Gardner (Lead Balloon and Fresh Meat) as the Lt Colonel, Katie Lyons as the blokeish Corporal Bird and a bomb-seeking robot called Arthur.

Last Tango in Halifax (BBC One) was very simply plotted, although, in contrast to a drama like The Town, writer Sally Wainwright's dialogue tended towards the emotionally incontinent.

"Why can't you accept that I want to be with Kate, that I am old enough to make my own decisions, and to accept it and be civilised about it?" wailed Sarah Lancashire's lesbian headmistress Caroline as she tried to drag her mother Celia (Anne Reid) into the 21st century.

A few scenes later and Celia had had a change of heart, declaring that she had "played hardball long enough" (perhaps the only 75 year-old in Britain to have ever used that term) and was ready to accept her daughter "for who she was" having been "on the road to Damascus".

Last Tango in Halifax was sometimes silly and two episodes too long. But it was that difficult beast, a comedy drama, and for all its faults could sometimes be both funny (any scene involving Tony Gardner as John, Caroline's feckless, needy ex-husband) and dramatic (any scene involving Derek Jacobi's Alan).

Pensioner Alan's late-blossoming courtship of Celia, his first love, was touching and the power came from Jacobi's understated performance. This theatrical knight has played many fascinating, complex men (Richard II, Francis Bacon, Alan Turing) but I have never seen him play ordinary. Often, great actors fail when they try to be the everyman; thwarted by their own heavyweight presence. But Jacobi as Alan achieved much by doing very little. Just by sitting in front of the Aga and sipping his tea thoughtfully, he vividly portrayed a kind, unremarkable man who had looked at life from atop his West Yorkshire farmhouse, and after three quarters of a century, had worked out its deepest mysteries. Amid the drama's silly theatrics of cheating spouses, concupiscent toyboys and alcoholic screw-ups, Jacobi added some much-needed depth.

The series has been a ratings success and will return next year when the grand and sometimes unlikeable Celia will prepare to walk down the aisle to The Entrance of the Queen of Sheba. Let's hope no pesky TV producer introduces an unfathomable story arc that will prevent her from getting her wish.

The once frosty Caroline (Sarah Lancashire) is thoroughly thawed, having re-evaluated her life during that long and worrying night when her mum and Alan were missing.

With a spring in her step, she returns to her enviably lovely house in Harrogate to tell her nearly ex-husband John that she is in love. Though with someone else entirely. The look of horror that transfixes his face is an absolute picture (no one can do baffled comedy-appalled quite like Tony Gardner).

Things are even looking up for Alan's daughter Gillian (Nicola Walker) up there on her chilly farm in the wilds, with all sorts of unsuitable men beating a path to her door. Ends tomorrow.

The classy silvery romcom continues. The vicar refuses to let Celia (Anne Reid) and Alan (Derek Jacobi) marry in church - well, neither of them has attended church since 1977 - so the second-time-around lovers go in search of venues for a civil ceremony. Soon they end up trapped inside a creepy medieval mansion in a storm, telling each other ghost stories. Elsewhere Gillian (Nichola Walker) tells John (Tony Gardner) he needs to stick up for himself, prompting him to return to Harrogate and tell Caroline (Sarah Lancashire) that he's moving back in.

Celia and Alan (Anne Reid and Derek Jacobi) are having a ball as the late-blooming romance drama beds in. They're racing through the gears of the relationship that escaped them 60 years earlier and, while their daughters are less than impressed, nothing touches Celia's wastrel son-in-law, John. Played by Tony Gardner, he is as gloriously dissolute here as he is creepy as Fresh Meat's Professor Shales.

Anne Reid as newly betrothed Celia has such a quiet-killer way of delivering a line; when her spineless twerp of a son-in-law gleefully explains the torrid sexual relationships in his latest book she fells him with, "Oh well, there we go." She might as well have shot him with a bow and arrow. Celia later explains to her fiancé, Alan: "He writes novels... they're nowt."

As Sally Wainwright's flinty romantic drama picks up pace, Celia and Alan (Derek Jacobi), reunited after 60 years, are planning an engagement party. Their respective families are still angry and baffled that the pair so suddenly decided to marry. Celia's unhappy daughter, who recently dabbled with lesbianism and who even more recently took back into her home the adulterous, novel-writing spineless twerp (the brilliant Tony Gardner), is particularly furious. But Celia and Alan don't care, they are too busy buying a sports car.

Celia (Anne Reid, mumsy with a hint of steel) and Alan (Derek Jacobi, twinkly with a hint of melancholy) are unbowed by the uniform opposition of their families to their engagement. In fact, while their children's private lives crumble (affairs, betrayals, midlife crises), their own bond looks stronger than ever. But could an engagement party reopen old wounds? As a portrayal of old age, it's not exactly 'Amour': the narrative signposting is constant and occasionally distracting. But what could have been whimsical - bordering on twee - is lent integrity by Sally Wainwright's characterisation, dignity by Reid and Jacobi, and drive by the goings-on among the excellent supporting cast, with professional scene-stealer Tony Gardner's oleaginous cheat as the stand-out.

Celia and Alan's touching whirlwind romance has been 60 years in the making. After dropping the bombshell on their children at the end of last week's episode that they're getting married, the newly engaged couple - played by Anne Reid and Derek Jacobi - have some exciting plans to make.

Not to mention bridges to build between their daughters Caroline and Gillian, who didn't get off on the right foot. "Trailer trash" and "b****" isn't the best way to greet your prospective in-laws.

So Alan and Celia decide to throw a little ­engagement party, which, as things turn out, should at least take the heat off their romance and stop it from being the sole topic of chat for a while.

This wonderfully bittersweet comedy drama from Sally Wainwright about love among the over 70s ticks all the right boxes thanks to sympathetic writing and excellent performances with depth.

Underneath Celia's twinkling optimism and girlish delight there lies a lifetime of experience and, when she puts a patronising young salesman firmly back in his box tonight, we can see exactly where her daughter Caroline (Sarah Lancashire) gets her take-no-c**p attitude from.

One scene tonight where Caroline cuts a meddling colleague down to size makes you want to stand and cheer.

Caroline's estranged husband John (played by Tony Gardner, who also plays Professor Shales in Fresh Meat) is back in the family home, but the appearance of his other woman (Ronni Ancona) is about to rock that little boat, too.