I'm aware of that but you used Libya as an example, where the mission didn't creep at all. support rebels, get civvies out of there, bomb gaddafi, help co-ordinate strikes, done then left them to it.
Or look at the French in Mali still going at it.
That said I think "mission creep" is a poor and misused term. Threats and the situation evolve. you cant keep doing the same thing a year later if everything has changed on the ground.
What should happen is, weigh how far we can commit, *dont announce it* and then work within that border, reassessing periodically. Again the french have been doing this brilliantly in Mali.
You've just succinctly named much of the mission creep in Libya. The UN resolution was solely about policing a no fly zone, it was NOT to take sides in the conflict. We did that. The government then said there would be no boots on the ground - that was one of the reasons it went through without being booted out of parliament. Unfortunately as the conflict continued more British forces were deployed on the ground, in part to evacuate, in part to coordinate with rebels and in part to train.
It's a prime example of mission creep.
I especially like this quote from this article
http://www.bbc.co.uk/news/uk-politics-12799937
SNP Westminster leader Angus Robertson asked about the "potential for mission creep", with Mr Cameron replying that the UN resolution was about protecting civilians: "I've been clear. I think Libya needs to get rid of Gaddafi. But in the end we are responsible for trying to enforce this Security Council resolution. The Libyans must choose their own future."
Angus Robertson obviously had some foresight...
I also like this.
Mr Cameron appeared to back Gen Richards, saying that "the UN resolution is limited in its scope. It explicitly does not provide legal authority for action to bring about Gaddafi's removal from power by military means.
Which we did. The rebels were a few weeks from capitulation and our intervention was the reason Gadaffi lost, after much of his military/security infrastructure and equipment was destroyed by target strikes from us.
Mr Cameron replied: "This is different to Iraq. This is not going into a country, knocking over its government and then owning and being responsible for everything that happens subsequently. This is about protecting people and giving the Libyan people a chance to shape their own destiny."
No, we went in, knocked out the government (see previous statement about resolution limits) and then left the Libyans to sort out the mess we left them in. Guess what, it's now a failed state. Nice to see not taking ownership of the ****storm that happened next was all part of the plan.
The whole "fool me once, shame on you. Fool me twice..." Comes to mind, and it's almost certainly (along with Iraq) the reason the motion to join in the Syrian conflict was voted down.
You are right, priorities change and new battles have to be fought that may not have publically been announced at the beginning of a campaign, unfortunately for the government MPs are starting to get wise of that, especially now it is becoming increasingly obvious that much of it is foreseen before any action is taken, they (and the public) are told. Especially if that oversteps the bounds of the resolution that the vote was based on in the fist place (like Libya).