If you think the Calcutta Cup is just any old rugby match between England and Scotland, then the latest in BT Sport’s fine series of documentaries should put you straight. It’s called The Grudge and is about the 1990 Calcutta Cup, the climax to the Five Nations with everything at stake for the first and only time: the Grand Slam, the Triple Crown, the Championship and the Cup itself. The film is narrated by the actor Robert Carlyle, so not entirely unsympathetic to the men of Scotland.

Craig Chalmers, looking slightly less boyish these days, chews the fat with Peter Winterbottom, who still looks like someone you wouldn’t relish packing down against. Flanker John Jeffrey sits on his Land Rover on his Borders farmland reminiscing while an amiable cow wanders by. Winger Tony Stanger smiles as he’s asked about the faint controversy over whether he touched down the decisive try in the epic 13-7 victory.

England weren’t popular north of the border so much then (were they ever?). Mrs Thatcher had just introduced the poll tax in Scotland, which hadn’t gone down well. Shipbuilding and steel were being hollowed out, and the previous year ‘God Save the Queen’ had been booed. This was the first outing for ‘Flower of Scotland’ at Murrayfield, sung with a fervour that would have raised the roof had there been one. As soon as the singing finished, Will Carling’s England, the strong favourites, realised they might be in trouble. Jeremy Guscott tried to catch the eye of his Lions teammate Gavin Hastings, but there wasn’t a flicker coming back. ‘Uh oh,’ thought Guscott. Hastings was in the zone.

The Scots coaches then, Ian McGeechan and Jim Telfer, good cop/hard cop, had a clear view of rugby as the great egalitarian sport. Telfer’s mother had been ‘in service’ with one of the big landowners from south of the border to pay for her son’s future. His team wanted to stuff it to the English – and who can blame them?

So it will be quite a test for Steve Borthwick, England’s new manager, at Twickenham on Saturday. Will England be like the demanding matron who’s ditched her flighty hedge-fund boyfriend to take up with the homely surveyor from down the road? We’ll see: Scotland tend to promise more than they deliver and have never quite lived up to that 1990 high point. England captain Owen Farrell is hitting rich form and Borthwick is clearly admired by his troops. In interviews he’s safe but uninspiring, so we will know soon enough whether there are hidden depths or just safe shallows.

The Six Nations is a guide to the World Cup but only just: the top two teams in the world, Ireland and France, will be on parade, as well as two teams who have just changed coaches, England and Wales. For entertainment you couldn’t ask for more, and the tournament lacks for nothing in scale; all it lacks is variety.

Also kicking off this weekend is the European Rugby Championship, with games in Bucharest, Lisbon, Tbilisi and Madrid. The following weekend play takes place in Amsterdam, Gdynia, Brussels and Heidelberg. This will (almost certainly) never happen, but imagine if the winner progressed to the Six Nations, and the bottom team in that tournament dropped down to the ERC. Georgia beat Wales in the autumn on merit. Imagine if they beat them in a game that really mattered – then there would be consequences of failure. Italy are getting better, too: if they don’t finish last in the Six Nations, Scotland or Wales would be dreading the drop. Imagine the Welsh having to beat England at home to stay in the Six Nations. Quite a game. The Six Nations with jeopardy, and the ERC with a prize worth playing for: maybe it’s not such a bad idea after all.