"I am a soldier, convinced that I am acting on behalf of soldiers. I believe that this war, upon which I entered as a war of defence and liberation has now become a war of aggression and conquest."

The first half of a double bill at the BFI Southbank of TV dramas directed by Jack Gold, this one focuses on poet-soldier Siegfried Sassoon and his 1917 declaration that he wishes to serve no longer in the British Army, risking disgrace and court martial.

In Tom Clarke's excellent play, Michael Jayston (a man who in his youth had a beautifully expressive face, described in a contemporary review quoted in the notes at the cinema today as 'sensitive yet masculine') is note-perfect as Sassoon, a man of bitter conscience who sees the first-hand waste of men under his command, and the fallacy of the reasoning behind continued conflict, despite being awarded the Military Cross himself.

Much of the play is a solo effort, where Jayston recites poems of Sassoon's in voiceover, either over scenes of otherwise contemplative quiet, or over conversations.

One particularly good juxtaposition is over a scene between Sassoon and a senior officer played by Clive Swift, while the poem (I think, 'The General') plays over the event; and another is where the poem 'Does It Matter' is heard just after the ill-fated Ormand, who dreams of a return to a life with no surprises, a wife, three children and a job as a bank manager, gives the matter-of-fact revelation that he has seen a man shot by his own officer 'just to get the others out of the trenches'.

There are other character parts who do less: David Wood as Ormand (who has a fun singing number in the mess); Michael Pennington as a brother officer, Cromlech, who has a hang up about class; Jonathan Cecil as a waspish Lytton Strachey; Donald Sumpter as the stammering, piano playing Wilmot; and a lively bosom-bouncing Ann Beach as a music-hall artiste who recalls Maggie Smith's turn in the film 'Oh! What a Lovely War'.

The play does not shy away from the horrors of trench warfare - there is a prolonged sequence in which Sassoon and Cromlech head out to the barbed wires where dead comrades are stripped of their greatcoats, trousers, and boots (Sassoon dislodges one man's leg during this operation and is promptly sick), and other dead men are seen rotting in the open, or floating under water with staring eyes.

It also makes clear the cost of any loss of courage, quoting and showing a notice which describes, dispassionately, the execution of three deserters.

Sassoon's statement of defiance is only précised here, although it is quoted in three different points throughout the film.

Our sympathies are purely with him, although his motivation is less clear than it may appear - is a personal, emotional, matter as Cromlech alleges, or is he indeed insane due a nervous breakdown as the Army supposes in order to quiet any insurrection from the ranks?

This is an excellent piece of work, which may benefit from some knowledge of the subject and his poetry, but which stands alone as a document of anti-war drama.

Gold directs well, with many scenes of Jayston in shadow, or on deserted beaches, or simply reacting in close-up to memories or thoughts in his head. Jayston is one of our best actors (these days you're more likely to see him in a guest role in one of our medical or crime dramas) and in the 1970s he did some genuinely excellent work, of which this is a prime example.

Oh, and if you're wondering about the title, Sassoon was called Mad Jack by his men because he was reckless, and one assumes, indeed courageous.