S2 E73: Who is the secret agent in UK cleaning sheds every night

Ever read - the Elves and the Shoemaker? This story is a lot like that, except, in this case, they aren't making shoes. Someone has been turning up every night in the shed of a 75-year old photographer who lives in the UK. This photographer used to leave his work shed in a state of chaos at the end of each day. But the next morning, he would find them spick and span. The contents strewn around would be collected and neatly kept inside a box. Curious to find out who this friendly elf was, he i...