According to the Daily Telegraph, MPs from both parties want David Cameron to ask the Queen to speak out in favor of the Union. This is a terrible, terrible idea.
The British Monarchy endures largely because successive Sovereigns have had the wisdom to stay out of the political fray. The Queen herself is famously averse to controversy, and I think she would be highly reluctant to stick her neck out on this issue.
Some have pointed to her remarks during the Silver Jubilee in 1977 as precedent for a royal intervention. But there is one key difference between 1977 and today: the Queen now has a separate set of Scottish Ministers who support independence. It would be constitutionally awkward (and politically risky) for her to speak out against their key policy.
The Queen is a smart woman. She knows that, despite Alex Salmond’s purported royalism, the SNP is divided on the issue of the Monarchy. If she maintains a solid relationship with senior party figures, they’re more likely to support the status quo. But that will be hard to do if she is on record opposing their most cherished ideal.
It must be hard for the Queen to hold her tongue on an emotive issue such as this, but if the Crown is to endure, she should follow the credo of her famous namesake: video et taceo (I see and keep silent).
 “I cannot forget that I was crowned Queen of the United Kingdom of Great Britain and of Northern Ireland. Perhaps this Jubilee is a time to remind ourselves of the benefits which union has conferred, at home and in our international dealings, on the inhabitants of all parts of the United Kingdom.”
 When the first Labour government entered office in 1924, it could easily have been a thorn in the side of George V. However, the King’s gracious behavior toward his new Labour Ministers took the wind out of the republicans’ sails, and Labour has generally supported the Monarchy ever since.