Anecdotal evidence from what people ride probably not super helpful since everyone has different riding abilities; probably best describing what sort of rider you are. Edmundro's advice seems pretty spot on - try leave your road bike in one gear for a week or ride around Richmond or up Highgate on a cruising/flat road gear - the largest gear ratio that you can cycle up those on will get you up anything in London.
Not someone with a lot of road cycling experience (I.e. long rides) despite having had a road bike. Yes this is a great idea, though I’m currently bikeless so can’t test.
Anecdotal evidence from what people ride probably not super helpful since everyone has different riding abilities; probably best describing what sort of rider you are. Edmundro's advice seems pretty spot on - try leave your road bike in one gear for a week or ride around Richmond or up Highgate on a cruising/flat road gear - the largest gear ratio that you can cycle up those on will get you up anything in London.