By Michael Mainelli Each week we ask a City figure to take a trip down memory lane. Today,Michael Mainelli, current Lord Mayor of London and Z/Yen Group chairman, takes a look back at his career. What was your first job? As one of six children, each having to pay our way through university, I had two school time jobs at school to save up – a precocious three summers doing research with American aerospace firm Martin Marietta, and the other a term-time one as ‘sanitation supervisor’ (janitor with a bit of proofreading) at a local paper. Strange but true. What was you first job in finance? I fir…