Ian Richardson (I)

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.

If a TV soap actor vacates a role, the character is wont to return with a new head on and no questions asked. When Heath Ledger died in the saddle, Hollywood drafted in a triptych of actors to complete the movie. But the sudden demise of Ian Richardson, 18 months after his first radio performance for 20 years, seemed to have spelled an end to the waspish comedy series, The Pickerskill Detentions, which I hailed in 2005 as "glorious".

Certainly, plans by independent producer Curtains for Radio to take it to television were ditched, presumably because only Richardson offered that elusive combination of bankability and credibility. Andrew McGibbon's creation, dark, satiric and with a hint of classical nemesis in every sting in the tail story, was too good to be lost to radio and it has returned in a new series as The Pickerskill Reports, undiminished by time and tragedy.

Ian McDiarmid has stepped brilliantly into the central role of the former schoolmaster, commenting from near and far on the malign activities of his former students, witticisms dispensed with vinegary glee, his plummy satisfaction as he outwits them conveyed with a baleful undertone. Each episode is an account of a different pupil who is outstanding for all the wrong reasons. However slippery the little devils are, they cannot outsmart Pickerskill, who has the forensic abilities of a murder squad veteran and the psychometric testing skills of an occupational psychiatrist.

His first subject is, in Pickerskill's estimation, a sociopath. He soon stumbles on Walter Hindle-Rand's plot to bribe the alcoholic maths master, dubbed the "meths master", with altar wine, in exchange for academic favours. Thomas Sangster played the boy in a performance in which the angelic facade of the choir boy was peeled away to reveal youthful cruelty in action. McGibbon's evocation of a boys' school in the sixties was like The History Boys stripped bare of idealism, a jungly training ground for the world. This was laugh out loud comedy, stabs of truth doled out with the humour.

Ian McDiarmid Interview

Shakespearean actor and Tony award winner Ian McDiarmid will be forever etched on the minds of cinema-goers as the evil Senator Palpatine in the Star Wars franchise. He is now stepping into the shoes of the late Ian Richardson to play a school headmaster in the Radio 4 drama series The Pickerskill Reports.

The first series of this fictional schoolmaster memoir, The Pickerskill Detentions, starred the late Ian Richardson as the crafty teacher who delivers rough justice to his more difficult pupils. That play packed such a narrative punch that, four years on, it's still fresh in the memory, and this follow-up promises to do the same. Ian McDiarmid takes on the role and pits himself against an apparently perfect choirboy who has a nice little sideline in extortion and theft.

A paean, in a way, to original thought, it's also a rumination on the sliding scale of crime and punishment and the difficulty of knowing exactly where to draw the line.