Whitechapel Bell Foundry is Britain’s oldest manufacturing company as it was established in 1570. They made the Big Ben bell for the Houses of Parliament and the original Liberty Bell.
The Whitechapel Bell Foundry’s museum is in their foyer, is open on weekdays and is free to visit. I found the staff very welcoming. They were willing to explain more about the exhibits and were happy for me to stroll around on my own too. Look out for the full-size Big Ben bell template over the doorway on the inside. Wow, it’s big!