The West Lothian Question was originally raised by the Scottish opponent of devolution, Tam Dalyell, who was the Labour MP for the Scottish constituency of West Lothian. His question was:
For how long will English constituencies and English Honourable members tolerate...at least 119 Honourable Members from Scotland, Wales and Northern Ireland exercising an important, and probably often decisive, effect on English politics while they themselves have no say in the same matters in Scotland, Wales and Northern Ireland?
In other words how long can the English tolerate the Scottish telling them what to do, while the Scottish would tolerate no such interference? This question was originally raised in the 1970s, but it was essentially a moot point. After all the Scottish narrowly missed out on their new parliament and so the English had just as much say over the Scottish as the Scottish had over the English.
In 1998 that changed when the Scottish and Welsh voted for their own devolved assemblies. Again this was not a big issue except when there were a couple of large backbench revolts over purely English matters when the government relied on Scottish MPs. For the first two Labour terms the Labour Party had more English votes and MPs than the Conservative Party, along with an (almost) English Prime Minister who sat for an English seat. However in 2005 this changed. The Conservatives picked up more votes in England, even if it was by a tiny margin of around 20,000 although they still had fewer seats. Scottish ministers sitting for Scottish seats were starting to hold English only portfolios such as health and transport and then Tony Blair was replaced by Gordon Brown who had spent all his life in Scotland, represented a Scottish seat and had a very obvious Scottish accent.
The West Lothian question was still on the back burner as David Cameron looked like he was going to win the election. However he did not. Instead he has to govern with the Liberal Democrats. If there are any big backbench revolts on English only matters the margin of victory for the opposition could be Scottish Labour MPs.
There is another issue, and that is money. A Scottish person receives a far larger amount of central government spending per head. On top of this there is a massive over-representation in parliamentary seats.
So in the middle of a difficult term will David Cameron try to stoke English nationalism by calling for only English MPs to vote on English laws? Don't bet against it.