I belong to a Facebook Group “Memories of London” and recently saw a post about the final resting place of the canons from the defeated army of Napoleon ! Here is a quote from the post.
“After the defeat of the French at the Battle of Trafalgar in 1805, the British started to strip the French boats and reuse anything of value. When it came to the cannons however, it was found that they were too large to be retrofitted onto British ships. Determined to find a way to flaunt their victory over the French, the British decided instead to use them as street bollards throughout the East End of London. This idea proved so popular that after the original cannons had all been used, replicas were made and these started to adorn more and more London streets. They continue to be made today, with their distinctive shape being an iconic feature of London’s streets. Although most of the original cannon-bollards have been replaced over the years, a few still remain..”
Sean Bryne
There is an original cannon on the South Bank near the Globe theatre. But here are a few photos of some replicas.
It is possible that some of these are the originals and have been painted and added on to. The British were happy to demote the cannon to bollards. The spoils of victory!
HorseAddict 
I’d love to hear from you!