The first in our walks podcasts features the River Lea in East London.    Marc  Z and Mr Londoner walk the lower section of the Lea to uncover the origins of India Pale Ale;  a tale of stranded Vikings;   how four Eton schoolboys ran an East End sporting empire;   the terrifying story of the St Paul’s bomb exploded on Hackney Marshes;   and the day when Lionel Messi played at the marshes.   Hear about WW2 bunkers on the Olympic Park,  the largest bell in the world,   the oldest tidal mill in history,  and how East End gas once lit up West End theatres.  Find out if there are any poplars left in Poplar, and hear about a 1960s American diner and floating lighthouse turned recording studio.