JB is the current Prime Minister of the United Kingdom, who previously served as Leader of the Opposition during the ministry of Tom Davis. He is a member of the Conservative Party and a parody of David Cameron.
His full name is never revealed, only ever being referred to by his initials "JB". He attended Eton and later Cambridge, along with many other members of his party.
Despite ostensibly heading up the progressive wing of the Conservative Party, it is mentioned by Peter Mannion that he and members of his "Eton clique" enjoy telling offensive and racist jokes to one another in private.
He is elected as the Leader of the Conservative Party and thus Leader of the Opposition at some time before the Specials. A younger modernist, he hires Stewart Pearson to try and broaden the party's appeal. Malcolm Tucker refers to his following in the party as "JB's barmy army".