The 5 most common pub names in the UK, in descending order, are; Red Lion, Crown, Royal Oak, Railway, White Hart. You can check a longer list at; www.jetlink.net/~bconroy/100plus.htm
According to CAMRA, the Crown is first with the Red Lion second. Until a few weeks ago, i always understood that the correct answer was 'Red Lion', however a few weeks ago on the BBC's "Test The Nation" they gave The Crown as the correct answer and fooled me.
At least it caused me to make further enquiries, in case it pops upin future quizzes.