Just a guess but when the author checks Siri on his phone it has access to GPS so is probably giving him the nearest 'London'. When he checks on HomePod it has

Just a guess but when the author checks Siri on his phone it has access to GPS so is probably giving him the nearest 'London'. When he checks on HomePod it has no GPS so gives him the most common 'London'. Although it's infuriating and we want these tools to be much better I'm not sure how Siri can really ever know which London he wants. A human assistant without context is going to need to make a guess too and isn't going to be right with that guess 100% of the time. It would make much more sense to request "London, England".