At Westminster, the two and a half main parties can all make an argument for relative youthfulness amongst their leaders. All three men were born in the late 1960s, making those of us born in the early 1970s wonder what we did with our lives. Policemen look a lot younger than they did, too. But I digress.

The Prime Minister is a relative grey-beard now. He’s marginally the oldest of the three, first elected to Parliament eleven years ago, and having run his party since 2005. His deputy and the Leader of the Opposition were both first elected in 2005, and all three come across as more youthful than any of their predecessors since Blair faced Hague.

Closer to home, the Tories and the Lib Dems both abandoned any sense that you need Holyrood experience to lead a Scottish party: both Ruth Davidson and Willie Rennie won their regional seats for the first time the same year they took over at the top. She’s the youngest on this list, but even Rennie is slap bang in the middle of the Westminster leadership age bracket. Green co-convenor Patrick Harvie has been at Holyrood significantly longer – coming up for ten years now – but he’s still not 40 (where’s next year’s party, Patrick?).

Conversely, the SNP and Scottish Labour are both led by politicians born in the 1950s, people who have been in and around leadership roles in their parties for a very long time. Johann Lamont chaired her party’s Scottish Executive Committee almost two decades ago, and Alex Salmond became his party’s leader the first time round in 1990. Both were first elected to Holyrood as part of the first cohort in 1999, although the FM took his ball to Westminster for the Scottish Parliament’s second session.

Why does this matter? Surely we needn’t sign up to the cult of youth? Of course not. One’s late 50s are a perfectly reasonable time to lead a political party, and experience still counts for a lot. But Holyrood, especially in the dinosaur head-clash between Labour and the SNP, has a sour partisanship that I believe is worse even than the mood at Westminster. Both these leaders have spent two decades glaring at each other across a narrow ideological gap (ignoring the constitution). Could this be an aggravating factor behind this petty-minded debating style? It seems unlikely that the tone could be lifted until these parties are no longer led from the 1999 intake.