What are the BBC's impartiality rules and is Gary Lineker bound by them?

The BBC has pulled Gary Lineker from the air and it has led to a growing boycott that has sent the broadcaster's sporting schedule into chaos. Lineker compared the government's new asylum legislation with 1930s Germany in a tweet, sparking the heated debate. Central to the row is the BBC's guidelines regarding impartiality - something supporters of Lineker have claimed hasn't been enforced consistently with other BBC figures. But what exactly are the rules, and do they apply to the sporting pundit? This video has the answers. Source: PA