This is a nice article from last weekend’s Observer, on how the civil service has been reacting to the hung parliament:
One thing is certain. Across Whitehall the yellow folders are being taken out of the bin and carefully read for the first time.
Civil service on a hung parliament
Published by
arbitrary constant 
If the author of that article thought “the blue folder was the only game in town” and that “across Whitehall the yellow folders are being taken out of the bin and carefully read for the first time” he or she should probably not be taken seriously as a guide to what was – and is – going on.
The article also continues a Guardian/Observer theme about coloured folders. Maybe some departments do it like that, but it’s not something I have seen in this election or any other. Anything which assumes, as this does, that it is universal practice takes an instant credibility hit.
Totally agree. All sounds so unlikely as to be a bit fishy.
See also this from today’s Sunday Telegraph. Sounds equally unlikely, I’d say.