There are loads round where I live (south Manchester). My GFs driving
instructor told her to treat them all as give ways irrespective of the
direction from which she approached. She passed first time so it must
have been reasonable advice :-)

It's an immediate fail if you actually drive through an unmarked crossroads
at speed - even if you are on the more major road (despite the fact that
generally speaking - most traffic on the more major road will simply drive
through without slowing)