The brinksmanship of SNP MPs over the vote to change fox-hunting rules at Westminster may prove to be counter-productive.

The attraction to his opponents of inflicting a humiliating defeat on David Cameron over a manifesto pledge is easy to see. The vote to relax the ban on hunting with dog packs could well be lost if Labour, who are opposing the measure, and rebel Tories are joined by the SNP members. But without the Scottish contingent, it will almost certainly succeed.

Anti-fox-hunting campaigners have put pressure on the party's 56 MPs to vote against the changes planned by the Conservative government.

The SNP traditionally operates according to the self-denying ordinance which sees MPs abstain on matters affecting only England.

Yet if they choose not to abstain this time, SNP MPs will be intervening in a vote which many see as very much affecting England only.

David Cameron has not opted for a straightforward repeal of the fox-hunting ban in England, but instead proposes to make changes to the existing Hunting Act. There are arguments that some of the changes to the Hunting Act which are proposed - relating to 'loopholes' allowing hunting for the purposes of research and observation - might undermine the effect of the law in Scotland by encouraging Scottish hunts to take a similar route.

But this seems pretty spurious. It is certainly hard to see the Barnett consequentials of a partial repeal of England's fox hunting ban.

This matters because there almost certainly will be battles ahead over what constitute 'English laws, and to what extent decisions in England that affect budgets in Scotland can possibly be seen as purely English votes.

The English Votes for English Laws (EVEL) debate could not be much more current, with the Government having only just conceded the need for more discussion, postponing a vote on its hugely controversial plans until the autumn.

This would seem to be a strange time to stoke resentment over an issue for which Scotland already has its own law.

Prior to the recent UK general election Nicola Sturgeon was clear. The SNP at Westminster whatever its representation, would be constructive, not obstructive. She reiterated that intention after her party's historic landslide. Reneging on the self-denying ordinance at this point would seem to be entirely contrary to that approach.

It may be that the SNP leadership feels it is necessary to show that their MPs will play hardball too, if Mr Cameron chooses to do so over EVEL and the limited greater powers on offer to Scotland.

But to thwart the intention of English MPs over fox-hunting, despite the temptation of defeating the government - and even if in principle SNP MPs disapprove of the proposals - would be a mistake.

It would be to fuel confrontation when diplomacy is what is required, playing politics in a short term and clumsy way.

The prime minister's official spokesman has indicated that the SNP would have to justify to its voters why MPs were voting on matters not affecting them. But the real challenge would be to justify this to English voters. An inability to do so might have malign consequences for the outcome of more weighty debates to come.