LONDON — The N.F.L. has long opposed sports betting and has more recently declined to invest in, or officially embrace, the daily fantasy sports websites that have caught on with fans in the United States and blanketed game broadcasts with advertising.
But in Britain, where sports betting is legal and which is now host to three N.F.L. regular-season games a season, the line is, well, blurry.
The N.F.L. signed a three-year deal that allows one of the major daily fantasy sports companies, DraftKings, which has been deemed a gambling outfit here, to post advertisements at Wembley Stadium, where the games here are played, but not on signboards near the field, so viewers in the United States cannot see them.