Is this the unanswerable case for SNP involvement in the next round of UK leaders' debates?

Well done to Stewart Stevenson MSP for spotting this incredible statistic -

"SNP now have 77 elected Parliamentarians, same as LibDems - Scot/Wales/UK/EU LD=5/5/55/12 SNP=69/0/6/2"

There's a slight error there, because the Liberal Democrats actually have 57 seats at Westminster. Nevertheless, if you take the SNP and their sister party Plaid Cymru together, they are clearly ahead of the Lib Dems by 92 to 79, which I would have thought is the final nail in the coffin of any notion that the Lib Dems have a 'national' presence that gives them a special entitlement to participation in televised general election debates that the nationalist parties do not share.

Of course the SNP shouldn't even need to pray in aid their strength in the Scottish or European Parliaments - their established position in Westminster politics ought to be reason enough. They have had continuous parliamentary representation since 1967, and are comfortably beyond the threshold of seats that affords official recognition as a Westminster parliamentary party. They outpolled both the Conservatives and the Liberal Democrats in one of the four constituent parts of the United Kingdom at the last election (in spite of the debates being rigged against them), and won more seats than the Conservatives. They also stood in 59 constituencies - two more than the number of seats that were required for Nick Clegg to become Deputy Prime Minister. And, of course, just like two of the three parties that actually did feature in the 2010 debates, they are a 'territorial' party, rather than a UK-wide one. However, if these facts aren't enough, the SNP's thorough-going dominance of the Scottish political scene over the next five years is going to make their total exclusion from the debates look ever more ludicrous.