"On his 'days out,' those flecks of light in his flat vista
of pollard old men,' it was at once Mrs Plornish's delight and
sorrow, when he was strong with meat, and had taken his full
halfpenny-worth of porter, to say, 'Sing us a song, Father.' "

A "pollard" is a tree which has had top cut off, so that it
cannot grow tall, and spreads out for ornamental effect.