Leader of the Scottish National Party Nicola Sturgeon has said her party's MPs will vote on English only health matters.
SNP parliamentarians have traditionally abstained from voting on English only issues as English MPs have no vote over a wide-range of Scottish policy decisions.
Speaking to the BBC's Nick Robinson, Sturgeon said:
We would be prepared to vote on matters of English Health because that has a direct impact potentially on Scotland's budget.
If there was a vote in the House to repeal the privatisation of the health service that's been seen in England to restore the National Health Service, we would vote for that.
Sturgeon conceded it was a "self-interested" position. She justified the stance by arguing that if the NHS in England had its budget cut that would have a "direct knock-on effect to Scotland's budget and our ability to protect the funding of Scotland's health service".
David Cameron has pledged a future Tory government would ring-fence NHS spending. Labour's new leader in Scotland Jim Murphy stirred controversy among the party's London MPs after he promised the proceeds of a mansion tax, which would overwhelmingly come from London, would fund 1,000 extra nurses in Scotland.
Sturgeon's intervention will no doubt whip up the debate as to the whether MPs outside England should be allowed to vote on matters that don't directly affect their constituents.
The Tories' answer the so-called West Lothian question has been to propose that only English MPs should vote on English laws. Labour oppose, who have 40 MPs in Scotland rejected the proposal.