He is the member for Barkshire because of his loud cough.
member for Barkshire
idiomA person who has a cough which causes them to sound as if they are barking.
Origin
disputed originA pun on member for Berkshire, i.e. a Member of Parliament for that district.
Since he started coughing so loudly in the quiet library, everyone jokingly called him the member for Barkshire.
The poor man could not finish his speech without a hacking cough, earning him the unfortunate title of the member for Barkshire among his colleagues.