A couple of quick points:
It's not a formal LibDem map. It's a map by the Liberal Democrats for Electoral Reform, or LDER - so a campaigning group of LibDem members, and one that represents a cause dear to LibDem hearts, but not formal LibDem policy. While the analogy's imperfect, you might think of the LDER as a LibDem electoral reform version of the ERG within the Conservative Party; they represent an issue that's important to the party, campaign strongly for that issue, and there's no doubt that they have a strong influence on party policy - but they do not set party policy, and their documents do not represent formal party policy.
All of that said... I thought the map was fairly straightforward myself, but perhaps that's because I'm more engaged with LibDem thinking. Urban seats get 4-6 members, rural seats get 3-5 members; the Western Isles and Orkney & Shetland continue to get single members (so that's one guaranteed LibDem seat - though also a guaranteed SNP seat). Colours on the map represent the boundaries of the proposed constituencies. So in Scotland, the three Ayrshire districts become a single STV constituency, while Fife is a single constituency
For a clearer map containing the full list of seats by constituency, you simply click on this link, which contains both the map and the full schedule (including the list of the local authorities forming each proposed constituency):
https://lder.org/wp-content/uploads/201 ... dule-1.pdfFor those of you desperately interested in the technicalities of seat apportioning, also
available via this link:
For simplicity, this scheme keeps the existing numbers of MPs from each of the UK’s four
nations, with overall total 650, only changing the way in which they are elected. Constituencies
are based entirely on Local Authority (LA) boundaries, electing mostly 3 to 5 MPs in rural
areas and 4 to 6 in urban areas, with a few exceptions dictated by electoral numbers and
geography
Once boundaries have been chosen, and a target quota of electors per seat fixed,
the entitlement of each constituency can be calculated; this is then rounded up or down to
a whole number, with the cutoff chosen to minimise the proportional discrepancy between
entitlement and allocation
The target quota is chosen so as to give the desired overall total
of seats (533, 59, 40, 18 for England, Scotland, Wales and Northern Ireland respectively).
Some typical constitutencies, with numbers of seats in brackets,are as follows: Bristol (4),
Liverpool (4), Glasgow (6), Falkirk & West Lothian (4), Cornwall & Scilly (6), Lewisham &
Greenwich (5), Yorkshire East (East Riding and Hull) (6), Bedford and Milton Keynes (4),
West Glamorgan (Swansea and Neath Port Talbot) (5), Northern Ireland West (Fermanagh
and Omagh, Derry and Strabane, and Mid Ulster) (4). Only one LA, Birmingham with an
entitlement of 10 seats, has to be split. Almost all the amalgamations fit with traditional
county boundaries; only three cross county council boundaries.
Perhaps surprisingly, given the rule of not dividing LAs, so that for example a constituency
with entitlement 3.51 gets rounded up to an allocation of 4 seats, the overall variability of
electors per seat, ±6%, is less than that of the current FPTP system, which was 7% when it
was introduced in 2007 and has since drifted out to nearly 10%. In contrast, the variability
of the STV system does not drift over time, because it can be updated very easily each year,
adjusting the number of seats in a constituency rather than changing boundaries; data for
England 2003-19 show that none of the proposed boundaries would have had to be changed
over that period, with the single exception of Leeds, whose entitlement has varied between 7
and 8; about a quarter of constituencies would have seen their entitlement go up or down during
the period. This stability in constituency boundaries, and their close fit to the structure of local
government, are major additional attractions to both voters and representatives, quite apart
from the basic motives of fairness, voter choice and proportionality underlying the scheme.