The first recorded mention of what we now call "fast food" in London were the "piemen" who hawked their wares through the streets since before the 10th century. Selling individual pies from barrows that they kept warm using hot coals, these were traditionally filled with eels caught from the River Thames. In those days they were available in such abundance that they could sometimes be seen swarming across country roads as they travelled from one ditch to another. By the end of the Nineteenth century their numbers had diminished to such extent that it was no longer possible to use them as pie filling and pie makers changed to using the mince beef that we can buy in Pie 'n' Eel shops in London today.
Pie 'n' Eel Shops:
Tower Bridge (near Sarsons factory),
Southend-on-Sea High Street,