"Walter's good nature and willingness to do what he is told makes him a good employee at the packing factory where he earns a living each day. The girls at work spoil him, to the annoyance of the other young men, who taunt and bully him.
"Walter's physicality was my prime acting problem. I spent a week with an ex-nurse who had tended mentally-handicapped patients at a large hospital. One of his methods of coping with the emotional burden of his job had been to meet after hours with other nurses and act out episodes from their working day. By mimicking their patients they released tension and learnt to sympathise with the handicapped. Stephen Frears dropped in each day - his most helpful comment was to tell me not to look intelligent - 'de-focus your eyes and it will seem that your thoughts are more confused and complete than your own.' It worked.
"I also visited a mental hospital outside London and observed the inmates, their gentleness and their clumsiness. Many of them had mouth disorders, so a plate of dentures was made to fit over my top teeth, making them bucked: usefully they made my diction a bit indistinct.
"Once I was confident that I could walk and talk and look like Walter (head slightly to one side, as if trying to catch the meaning of his surroundings) I wanted to test whether I looked convincing to other people. So I dressed in Walter's trademark flat cap and tatty overcoat and accompanied by my 'nurse' went out in public.
"In Marks and Spencer's in Upper Street Islington North London, 'Walter' made a bee-line for the rack of ladies' underwear and giggled to himself. Then he grabbed a packet of humbugs and pushed his way to the front of the customers queuing at the cash-register. The woman who was first in line turned to remonstrate that I should wait my turn. But in response to Walter's innocent, toothy grin, she relented: 'That's alright dear, you go next.' Walter smiled back and the actor thought 'I think I've got him.'
"Just to make sure, we went to have a pub lunch in the King's Head, home to a theatre-club where I recognised some actors having a drink. They didn't notice me, even as I spluttered my way through beans-on-toast. The dentures made chewing nigh impossible. But Walter's outing had been a success. From then onwards I found it easy to drop into his mannerisms and the major acting problem had been solved."
"The scenes in Walter's home were shot on location as was the entire film. The muted colours of the costumes and the natural lighting designed for the hand-held camera of Chris Menges' photography, all helped to establish a documentary feel."