Much as I love the egg-chasing game, it has always struck me as rugby's most profound weakness that it has nothing in its repertoire to match the sublime moment of sporting purity that is football's own goal.

Touch the ball down behind your own line and the worst that will happen is a five-metre scrum. Knock one into your own net and you'll have to put up with the scorn of your team-mates, the taunts of your opponents, the derision of the crowd and about a billion hits on the YouTube compilation over the next few years.

It's easy to understand why. No playwright could ever contrive a scene of such exquisite drama as this goalmouth frieze of shock and despair, accusation and recrimination. It is melodrama and farce in one perfectly formed package, a scene of intense emotional turmoil as the hapless defender sinks to his knees and the other team struggle to contain the urge to kiss the fellow on the forehead.

Rugby is denied all this. Or rather it was until last week, when a group of Scottish 'legends' - a term that has clearly acquired a certain flexibility of late - gathered at Murrayfield to pledge their support for the referendum No campaign. Finally, rugby had its own goal.

As it happens, I have a lot of time for people such as David Sole, Gavin Hastings, Finlay Calder and the rest of them, just as I had a lot of admiration for them as individuals in their playing days.

I also couldn't really care less whether they favour Yes, No, Maybe, Revolutionary Socialism or Church of the Militant Elvis Party (which took a heroic 112 votes at the 2010 general election in Kettering). But for them to come together as they did, and where they did, was a monumental misjudgment.

By way of clarification, they weren't actually in Murrayfield, the Scottish Rugby Union having made it crystal clear that they wanted nothing to do with the stunt. Instead, they hung about in Roseburn Street, just outside the stadium, which is where most of the photographs you might have seen were taken.

(At this point you might also recall that the SRU recently appealed for former international players to take part in a study to examine whether their mental faculties had been damaged by repeated head knocks. You will be pleased/relieved to know that I am making nothing of this intriguing twist in the narrative.)

Now it can be dangerous to generalise but, from a brief look at the group shots of the former players, I reckoned that between two-thirds and three-quarters of them had attended private schools. A clear majority are Edinburgh-based. All had been retired a long time. All, of course, were male. Or, to put it another way, a bunch of well-off, middle-aged blokes want things to stay just the way they are. Staggering, isn't it? Who knew?

Well, most of the pollsters for a start. Which is why the number of votes added to their cause by this gathering is probably about the same as the number of points Scotland put on the scoreboard against England last February.

At the very moment when the referendum battleground had moved to working-class west of Scotland, these old rugby bods were about as far from the frontline, in every sense, as they could be. Frankly, it's a wonder they didn't wait until after September 18 just to underline the pointlessness of it all.

Except, of course, that it played right into the hands of Yes campaigners. Yes, these stars of yesteryear had just knocked one past their own 'keeper with their gesture. They might not have been in quite the same league as Nigel Farage in that regard, but there are still plenty of people in Scotland who can be persuaded to go in one direction by the knowledge that affluent establishment types favour something else. And there are many people in Scotland for whom rugby still means affluent establishment types.

"What on earth were they thinking of?" was the comment of someone I met the following day.

Now I have absolutely no idea whether the fellow who said this was in the Yes or No camp, but politics was not the issue for him. Instead, what incensed him was the fact the grey-templed Roseburn flashmob's reinvention of themselves as some sort of rugby Bullingdon Club only reinforced an image of the sport as the game of a privileged elite.

Yes, you can pick through the pictures and find John Rutherford and Colin Deans - both state-schooled in the Borders - in there as well, but the clear majority are from a different social sphere.

Does this matter? Hugely. You can quibble over just about anything in this game - tactics, selection, league structures, governance - but the one overwhelming issue that holds Scottish rugby back is that its social and demographic base is far too narrow. It always has been.

Despite the heroic hard work of many people at clubs and even in schools, the gains have been modest.

Consider the line-up for this season's Brewin Dolphin Under-18 Scottish Schools Cup, which has just begun. Sixteen teams: every one of them in the private sector. Now there are many reasons for this, and there is no point whatsoever in pointing the finger of blame at those sides who take part or those sides that don't, but it is a staggeringly unhealthy situation.

Do you think for one moment that it would be allowed to happen in New Zealand? Almost eight years have gone by since, after a humiliating series of defeats at age-grade levels, senior SRU officials talked about how the nation's youth were being failed by the game's rulers. Scott Johnson, now national director of rugby, spoke recently of the need to widen the game's reach. It really would be the ultimate own goal if that did not happen.