There have been a couple of 12 month deals for the Galaxy S2 posted recently, but this option seems to work out the cheapest and best value.
The details are...
£75 upfront for the phone
£35 x 12 months = £420
Then, the deduction of Quidco (£50) brings it down to £445, making it the cheapest overall cost I can see anywhere at the moment (£19 cheaper overall than the e2save deal posted last week).
The 12 month contract length has to be the best part of this deal. You get the latest Samsung smartphone with a decent amount of minutes, unlimited texts, plenty of data, and the opportunity to upgrade in a year.