Who is The Brookers from The Road to Wigan Pier and what is their importance?

Mr. and Mrs. Brooker form a landlord couple who rent Orwell a bed during his several-weeks' stay at Wigan. In addition to their boarding house, they run a tripe shop from the same establishment. Mrs. Brooker is hugely fat and suffers from a diffuse and unspecified ailment which Orwell suspects is simply obesity, coupled with continual overeating and depression. In any event, she spends day and night on a collapsing sofa in the downstairs parlor of the boarding house and does no work.