It's from the downtempo/chillout group Nightmares on Wax, working a roots rock reggae sound with a beautiful dubby bass lick. (Note: hope you have a subwoofer).
When I first heard it on XPN last week, I thought it was a remix of an old reggae track. But it looks like they did it live in the studio:
The great thing about that track is that Ricky never even came to do that track; he came to do a different one that didn’t actually make the album. We finished pretty early and went to get some [stuff]. We got back and just knocked this beat together. I was saying let’s do something new, knocked a beat together, and he was freestyling. I said yo just go in the studio man, just go in the booth, and I just pressed the record button, and he freestyled the track. That day we had been talking about social issues and the way things are, between riot police on the street, and this was when all the ASBO stuff had just kicked in, and he was pretty freaked out by it all. So the actual influence of the day and that track is about how people should just calm down and take time out for each other. (link)
And this is what Brainwashed says about the track:
No true roots reggae devotee could possibly pass over the sun-drenched "Flip Ya Lid", with classic toasting, subtly dubby echoes, and a bassline begging for a massive sound system.
Massive is fine, but even headphones and an Ipod is fine on a track this nice.