Sturgeon has played this very cannily. Voters in Scotland believed they’d vote SNP and get a labour government that the SNP could screw for concessions in exchange for support. English voters were wary of voting for a weak labour government that would be compelled to capitulate to the SNP, particularly with all the bad feeling that was whipped up during the referendum with reports of Scotland getting a better fiscal deal than the rest of the UK. This unsurprisingly pushed more English voters towards the Tories. The final part of the plan will be if the rest of the UK vote to leave the EU, triggering another referendum. I imagine she was hoping for a few more UKIPpers to help this along, but that’s not vital. I was dead against independence, but given a choice between that and staying in a UK that was out of Europe even I would probably change sides. So, good result for the SNP, but about as bad as it could possibly be for the rest of the UK.
I always thought it sounded a bit odd that the French ambassador would just make up the comment from Sturgeon that she would prefer another Conservative government.