he worked his way through amys suggestion that he deal with his boredom , making up a threat from her to go back to her mother if he didnt get a hobby and adding a few fictitious details about how hed tried knitting and candle making , but could never compete with the street vendors , for whom a penny profit on a days work was adequate , and anyway the doctor had told him that walking was essential for the leg hed got injured heroically in the line of duty , and how hed decided to revisit some cold cases , and what a joy it had been to be wandering the streets of london just before christmas .