Quick, pull up the drawbridge

Who invented the computer? Some say it was Konrad Zuse in 1938, while others point to the Victorian Charles Babbage (even though it's rude to point), but they're wrong, because a document I found buried deep inside my imagination suggests that it was Willem Gaytes, who launched his Windows 98 back in 1498. Apparently, his program had to be stored on vast, leaded windows, while the computer had a wooden hard disk, and used a real mouse to control the system (it ran around on a hamster wheel, connected to a tiny generator); but sadly, Squire Gaytes's Windows 98 was prone to crashing, thereby leaving fragments of stained glass all over the place. Thank heavens for our modern consumer laws, which nowadays would never allow a product with such an obvious design flaw to reach the market.

Some dodgy medieval software seemed to have been used to generate the absurdly primitive computer graphics on last night's Bloody Britain (Discovery).

This "look at some of the bloodiest moments in British history" sought to bring the gory 13th century siege of Rochester to life, but singularly failed in the attempt, mainly due to its desire to create Brobdingnagian effects with Lilliputian resources. The animated sequences used techniques that even the Noggin the Nog team would have rejected as too simplistic, while the epic battle for control of the castle lost much of its effect because the budget had enabled the programme-makers to hire only two extras for the fight scene. "You can imagine the mad activity of the knights on horseback and the bowmen running," said the presenter, Andy Riley, and indeed I could; but if I have to imagine the action for myself, then what's the point of watching television?

The presenter and his notsospecial effects began taking us through the story of how 100 rebel barons had defended Rochester castle for seven weeks against bad King John and his mercenaries, in the autumn of 1215.

But the real villain of the piece turned out to be Mr Riley himself, a man who is manifestly too fat, too bald and too old to engage in an Ali G-style "boyakasha" finger-slap (seemingly without a shred of irony). His attempt to make history seem what young people call "cool" (don't pronounce the final consonant, by the way) may be well-intentioned, but it only succeeded in making the subject seem trivial, especially when he also started drawing silly cartoons, in the manner of Rolf "can you see what it is yet?" Harris.

And when he went on to say, "what we're talking about is the most gory and gruesome event", I very nearly switched off - not because I don't like gore and grue, but because ever since the day Lady Thatcher announced that "we are a grandmother", I've regarded the desire to speak in the first person plural as a 100 per cent certain sign of incipient madness.

Nevertheless, like a true professional, I kept watching, as John's men attacked the castle walls, and the barons became so hungry that they could (and did) eat a horse. Not that we saw any of the men, of course, except for the pair of "medieval reconstructionists" mentioned earlier, who I suspect belonged to the Historical Educational Recreational Beardies Enacting Repugnantly Theatrical Scenarios society (or HERBERTS for short), though we did witness a replica trebuchet in action, hurling rocks into a nearby lake.

Apparently, the keep was eventually breached by the simple ruse of lighting a huge fire of pig fat beneath the floor and waiting for it to collapse (obviously, the castle was constructed by typically British cowboy builders), and the barons were forced to surrender, in spite of a last-ditch defence, dutifully re-enacted by our two Sealed Knotters in chain mail. A thought: did medieval knights use condoms made out of armour? And if so, were they referred to as chain mail letters? All right, it's half a thought.

Robert Fitzwalter was the Lord of Dunmow and called himself Marshal of the Hosts of God ... so, no ego there then," smirked Mr Riley, whose own enormous ego was all too visible throughout an unoriginal and unimaginative programme that will very soon (I pray) be history. Even the idea seemed to be derived from the AA's Bloody Britain book (although I didn't see it credited), and the only genuinely interesting moment came with a reference to Richard the Lionheart and the Crusades, which reminded me that the origins of the current rivalry between the Cross and the Crescent go back a very long way.

I myself come from an ancient family of grist-makers (we used to supply it to mills), and it does my heart good to see the Crusades getting going again, just like in the old days.