The link below shows where Britain's Olympians came from. You select an area, then click on a sport and it tells you if your area is pulling its weight in that field. https://www.joininuk.org/wheretheystarted I was shocked to discover that Glasgow is slacking in the cricket department.
To be fair, everyone is slacking at cricket apart from Devon and Somerset. Cricket's only been played at one Olympics and Devon & Somerset Wanderers represented Britain.
London's the best by quite a long way really, look at the gold medal chart Particularly impressive are the boxing and athletics stats The cricket and Rugby maps London has produced 0 Rugby players.