Why doesn’t the Speaker icon on Google Translate appear on Firefox

Just click the url and you'll see that the page content has been translated.

A few months ago, this issue was on TV news and it was also a trending topic in Turkiye. Turkish to English translations of some famous Turkish people were shocking. Here are some examples:

Turkish          English
-----------      --------------
Hande Yener      Marilyn Manson
Ferhat Göçer     Justin Timberlake
Mahmut Tuncer    Jennifer Lopez
Demir Demirkan   Iron Maiden
Edip Akbayram    Slipknot
...              ...

They said it was because of some mischievous collaborators who like abusing Google's translating system through Google Translate API. This got to be the same case for your London example.