Trust The Guardian to do it again. Just look at this elegant solution to depicting the complex network of international jihadists and mosques in Britain.
It’s a sort of triple Single Bubble. Each venue (mosque or club) has its radial connections of people. With three such venues in the centre, it’s possible also to show how certain individuals are connected to two or more venues. Additionally, the individuals are grouped by country.
This is a clear and concise visual solution to unlocking the complexities of this situation. If not this method, how else could it have been achieved?