Royal Cousins at War, BBC Two

World War One overkill - if you'll pardon the expression - is a clear and present danger as the centenary commemorations gather pace, but this investigation of the roles of the interlinked royal families of Europe in the onrush of hostilities was as good a chunk of TV history as I can remember. Informative and detailed but always keeping an eye on the bigger picture, it made me, at any rate, start to think about the road to 1914 in a different light.

The pivotal figure was Queen Victoria, whose influence we could see reaching far beyond the immense era named after her and onwards into the later 20th century. The bellicose Kaiser Wilhelm II was her grandson (his mother was Victoria's oldest daughter Vicky), her granddaughter Alix of Hesse was the wife of Tsar Nicholas II, and her grandson George V was on the British throne when war broke out. Thus the rulers of three major combatants were cousins with close ties to the British monarchy, and one can only imagine the Old Queen's horror had she been alive to witness the war's ravages and its obliterating impact on her extended family (below, the Kaiser and future Edward VII, on right at rear, with Queen Victoria and daughter Vicky).

But possibly the most illuminating portion of the film concerned  the little-known influence of the Danish royal family in the later years of the 19th century. Victoria's son Albert (later Edward VII) married Denmark's Princess Alexandra, and Alexandra's sister Dagmar (aka Minnie) married the future Tsar Alexander III. Every summer, the Danish royals kept an exceedingly laid-back open house to which their British and Russian in-laws were cordially invited. Also in attendance were representatives of the various lesser provinces which had been conquered and subsumed by Bismarck and the Prussian war machine as it marched towards the unification of Germany in 1871. The Prussians themselves were pointedly omitted from the Danish guest list, which served as a curious advanced warning of the way the battle lines would be drawn up in the apocalyptic late summer of 1914.

The prescience of Queen Victoria was another recurring theme, even if it was undermined by the law of unintended consequences. As she pointed out to her son Bertie, "your whole family are German and you are half German." It was with a view to exerting a civilising influence on the brashly militaristic Prussians that Victoria sent daughter Vicky to marry the Crown Prince Frederick, having primed her carefully (according to this version at least) about the importance of her diplomatic mission. It might have worked too, since Vicky and Frederick made a notably enlightened and liberal couple. But complications during the birth of their son Wilhelm, the future Kaiser who went to war, left the child with a disabled left arm. Evidently his feelings of shame and inadequacy in Prussia's macho, militaristic culture festered into a kind of crazed belligerence, and we know all too well where that led (below, Tsar Nicholas II, Alexandra and family).

What little light relief was on offer came from accounts of Kaiser Wilhelm's visits to the Cowes sailing week (his attitude towards Britain kept veering berserkly from loathing to fawning groupiedom). Loud, aggressive and cursed with a grossly infantile sense of humour, Wilhelm pissed off just about everybody, and each year at Cowes he would crank up the personal arms race between himself and Bertie, now Edward VII - he'd bring a bigger, flashier yacht, or come with a retinue of German warships which fired their guns at uncouthly inappropriate moments, or arrange for Zeppelins to fly overhead. It began to sound worryingy like a tale of sound and fury, told by an idiot.