With the nostalgic Right grumbling about a curriculum bereft of heroes, English teachers know they can always call upon the services of Henry V. He can be relied upon to bring a flutter to girls’ hearts, and inspire red-blooded boys of all ages to want to imitate the actions of the tiger.

But teachers with heroism in mind should think twice before allowing them to witness their hero’s misspent youth, as recounted in this BBC adaptation of Henry IV. It shows Hal to be nothing less than an utter bounder. What self-respecting child would want to go once more unto the breach, following a man who so callously betrayed his best pal?

Forget the Machiavellian skulduggery at court or the rebels’ foolhardy adventure, the real treachery in this play - the stuff that will outrage a young audience - is Hal’s mistreatment of Falstaff. True to the text, in Jonathan Firth’s portrayal of a resolute and self-aware Hal, there is never any doubt about where his loyalties will ultimately lie: we know that he’ll be back at court the moment he calculates that there’s something in it for him. Handsome, self-centred and sneering, he is the classic school bully enjoying a little idle fun at Falstaff’s expense before setting forth to embrace his destiny of being A Good Thing.

Pupils, with their innate sense of natural justice, will long for him to get his come-uppance. They’ll cheer for Hotspur in the duel scene, and certainly hiss Hal’s final and unforgivably icy “I know thee not, old man”.

This production merges the texts of Henry IV Parts 1 and 2 by some shrewd editing of Part 1 (but it is a shame Glendower ended up on the cutting room floor) and ditching all the tedious rebellion from Part 2. The ragamuffin army of comic characters survives: Mistress Quickly (Elizabeth Spriggs), Doll Tearsheet (Jane Horrocks), Justice Shallow (Paul Eddington), Silence, Bardolph and Poins.

It’s odd that a play can be so gloomy when it has such a marvellous collection of eccentrics, so much comic dialogue (even Hotspur can be wonderfully acerbic), plenty of tomfoolery and some genuinely comic scenes. But this production is all candlelight and long shadows - infirmity, the ague, hangovers, regrets, wistful remembrance of things past, and the ever-beckoning gaping grave.

Not just the King (played by Ronald Pickup) but all his courtiers seem “wan with care” ( it’s no surprise that Hal gives the court a wide berth). Falstaff should offer an alternative but despite the badinage and bravado, in David Calder’s sensitive performance he really is blown up like a bladder by a plague of sighing. He and his chums might get legless down the Boar’s Head but it’s to drown their sorrows rather than celebrate joie de vivre. All in all, it makes for a very downbeat evening’s viewing.

In the theatre, of course, the audience’s shared laughter acts as a suitable counterbalance to underlying melancholy. Home alone with the television there’s no escaping that unremitting message that, whether you choose the primrose path or the straight and narrow, being a grown-up ain’t much fun. And that, perhaps, is another good reason for teachers to think twice before encouraging pupils to watch this production.