Maps elsewhere: Mapping the leaked BNP membership list

A few weeks ago, a disgruntled former member of the far-right British National Party leaked the party's membership list. The Guardian explains:

Every police force in the UK was tonight scouring the leaked British National party membership list for names of serving officers, after the Merseyside force confirmed it was investigating one officer's links to the far-right party.

The Prison Service pledged to oust any employee on the list and far-right supporters spoke of fear for their livelihoods as the BNP was plunged into crisis.

...Around 13,000 names and addresses appear on the list. It is thought to include a number of lapsed members and possibly the names of individuals who contacted the party and expressed interest in joining but did not do so.

However, the BNP has confirmed that it is essentially a genuine membership list. It includes the names of a number of clergymen, an actor, two solicitors, at least one doctor and a number of primary and secondary school teachers.

Full story

Both the Guardian and the BBC's Map of the Week have presented the data as a map. They took different approaches:

The Guardian's map (link) mapped the list by constituency using Flash, with a limited number of areas clickable. It's more or less impossible to get a sense of the underlying geography. Also, limiting the number of clickable polygons means some questions aren't answered. What is the constituency between Glasgow and Edinburgh which has the highest BNP membership in Scotland? There's no way of finding out.

The BBC's map (link) mapped the list by postal area, presenting the map as a 432x500 .jpg covering all of Britain, which limits the reader to noticing general regional patterns:

...There is a spine of BNP support running down the Pennines from the former Northern English mill towns of Blackburn, Burnley and Bradford to Derby, Nottingham and Leicester in the East Midlands.

Their choice of colours is more intutive than the Guardian's map, to my eye.

However, both maps use the absolute number of party members in any given area, while I think it would be more meaningful to look at membership per 1,000 of population. This is particularly important when using postal areas where (unlike electoral divisions) there is no real attempt made to make them equal in population.