OK, short version: no.

And logically this makes sense, because you can see the pub problem as a subset of locations within all locations, and all of these pubs are clustered around an equidistant point at ~72 minutes from everywhere in London. If such a location existed, it would have to be within that cluster, but somehow an average of > 12 minutes travel to all those pubs in that grouping. An eye ball test on a map tells you that isn't possible.

You might be asking "is there another location without pubs that is more equidistant", and mathematically that could yield a coffee shop, except in London it won't because the equidistant point for all of London and the equidistant pub basically are at the same point to within hundreds of yards, because of how public transport and public houses are distributed across all boroughs.