Can you please identify this mosquito-like insect?

I’ve seen these insects before (here in Cambridge, UK) and thought that they were probably mosquitoes, but they don’t make the annoying noise that mosquitoes do (they fly similarly, but silently):

I also noticed that they are perhaps slightly larger than mosquitoes (maybe 12mm long) and don’t have the long mouth which mosquitoes use to sting you.

Sorry for the poor photos, I don’t have a camera with a macro lens anymore, and it’s night-time. It’s casting a strong shadow as you can see in the second photo.