Where there are cross-party groups there are, alas, also often cross parties. Sammy Stein is one of them.

The pro-Israeli activist wanted to sign up for what is essentially a private body deeply opposed to his world view.

Nobody should be surprised Mr Stein was refused entry in to the Cross-Party Group or CPG on Palestine. The chairman of Glasgow Friends of Israel may style himself as a “Palestinian” - because he was born in the Holy Land - but few members of the CPG would see him that way.

READ MORE: Pro-Israel activist refused permission to join cross party group on Palestine

The SNP supporter may as well ask whether his own party would accept a membership application from Scottish Conservative leader Ruth Davidson. Would active opposition to full Scottish sovereignty and the Scottish Government be a barrier to membership of the SNP? Yes, it would.

Mr Stein says that his rejection - and that, he pointedly records, of two other Jews - was undemocratic and unfair. The Scottish Parliament did not agree. Holyrood authorities have supported the group against Mr Stein.

Essentially the activist is objecting to the very nature of a CPG. That is a debate Scotland has not had. Nor has the UK Parliament, which has similar structures. They have alway been seen as useful forums for like-minded politicians and other interest groups. Pro-Israelis, it should be said, have one at Holyrood too.

CPGs, the parliamentary website says, ‘provide an opportunity for Members of all parties, outside organisations and members of the public to meet and discuss a shared interest in a particular cause or subject”.

READ MORE: Pro-Israel activist refused permission to join cross party group on Palestine

Such groups come and go, depending on the passions of members. Some are more active than others. Some are controversial. Others, not at all. There is a CPG on arthritis, one on volunteering and another tourism. But there are also CPGs on difficult geopolitical areas.

And that, traditionally, is where some rather sticky issues crop up.

In the early years of parliament, CPGs tended to reflect the politics of student unions in the 1980s. There was group on Cuba - it is still there - but not one on Germany. That Cuban CPG has its secretarial services provided by a body campaigning in support of the Communist dictatorship.

There is a CPG on China to which the consulate of another Communist dictatorshp is invited to attend. There are also CPGs on Tibet and Taiwan, whose members may not be quite so welcoming to leaders of the current Beijing regime.

The CPG on Russia used to get input from the government of Vladimir Putin. Late last year, under new leadership from Green MSP Andy Wightman, it held a meeting on Kremlin propaganda from which representatives of regime-funded media were barred.

Issues like Russian propaganda or Chinese soft power or the Israeli-Palestine conflict all have a direct impact on Scotland and Scottish politics. But here is the rub, Holyrood is primarily a legislature concerned with devolved issues. “External relations” - despite their importance to our life and even directly to devolved politics - are relegated to an after-thought in the committee structure where they bundled together with culture and tourism.

READ MORE: Pro-Israel activist refused permission to join cross party group on Palestine

Therefore Mr Stein may have reason to be a cross party. He was never going to get on the CPG on Palestine. He may well find a home on one devoted to Israel instead.

But does the Scottish Parliament need more space to discuss global affairs across traditional dividing lines? That might be a cause worthy of its own CPG.