They promised a referendum on the EU
The Scottish vote was pointless, they’d still be ruled by Brussels
In that case, no, they didn’t “lie plain and simple” or at all.
Proposed referendum on United Kingdom membership of the European Union
> In January 2013, British Prime Minister David Cameron promised an “in/out” referendum on British membership of the European Union in 2017, after a period of renegotiation with the EU, if the Conservative Party wins an outright majority at the next general election, on May 7, 2015.
http://en.wikipedia.org/wiki/Proposed_referendum_on_United_Kingdom_membership_of_the_European_Union
But if Scotland *had* voted themselves off the island (55-45 to stay in the UK), the EU might have thrown them back.