David Moyes entered the debate over whether the Old Firm should play in England last week by saying that his former club Celtic, and city rivals Rangers, had fan bases large enough to increase television revenue and boost finances were they to join English football. And that is exactly why Scotland can't afford to let them go.
The SPL has had well-documented financial difficulties in the past twelve months. After the collapse of Setanta, there were genuine fears in Scottish football that teams in the top flight would not survive the financial drought that followed. Only a late deal with Sky Sports and ESPN prevented the season starting void of guaranteed income from TV rights, and the deal that Scotland's top 12 teams were left with is worth only half of what they expected to receive from the previous Setanta deal.
A cursory glance at the ESPN and Sky Sports schedules shows that they agree with Moyes. Live coverage of the SPL is dominated by the Glaswegian sides, with only the 'best of the rest' featuring alongside. It is these games featuring Rangers or Celtic, in particular the Old Firm derby, that generate some level of broadcasting interest in the SPL.
Should the Old Firm make the journey south, broadcasters are unlikely to abandon the new SPL altogether. But given the present lack of interest, it is hard to imagine that similar amounts of investment would be forthcoming. It is unlikely that Hibs would be able to attract players of the quality of Stokes, Riordan and Miller on a significantly reduced budget, whilst their counterparts across the city would struggle to keep players like Nade, Stewart and Driver. The SPL risks losing its talent.
So whilst Scottish football would survive, it would not have even the limited gravitas that it currently clings on to. Competition would increase, but quality would collapse. The SPL just wouldn't be the same.