Comet 2006 P1 McNaught is now definitely visible in broad daylight.
See http://www.spaceweather.com/ for more information, and a photo from Switzerland taken just a few hours ago.
The weather for the south of the UK tomorrow is clear and sunny, so there's a good chance you'll be able to see it for yourself.
This is a once in a lifetime opportunity.
Just block the sun's glare with anything to hand (eg stand in the shadow of a buiding) and look about a clenched fist's at arm's length distance to the left of it.
