I would suggest if you don't already you should follow @AndyJSajs
This is some great work by him showing how the electorate has changed from 2014 to 2015
Parliamentary electorate:
1st Dec 2015: 44,722,004
1st Dec 2014: 45,325,078
Spreadsheet with constituencies ranked by numerical drop between 2014 and 2015. Constituencies in red are below the lower threshold, green the higher:
docs.google.com/spreadsheets/d/1-H4eqc43aDRvF9V_VOjTQRh-rPmNifYJom-yaJ79Rpg/edit#gid=0
Top 20 gainers in percentage terms
Constituency | Party | 1st Dec 2014 | 1st Dec 2015 | Change | Change % |
TOTALS | #REF! | #REF! | #REF! | #REF! | |
Bath | Con | 56,986 | 60,966 | 3,980 | 6.98 |
Liverpool, Riverside | Lab | 63,264 | 67,054 | 3,790 | 5.99 |
Loughborough | Con | 69,933 | 74,069 | 4,136 | 5.91 |
Nottingham South | Lab | 61,884 | 65,512 | 3,628 | 5.86 |
East Devon | Con | 72,670 | 76,372 | 3,702 | 5.09 |
Plymouth, Sutton & Devonport | Con | 65,754 | 68,987 | 3,233 | 4.92 |
York Central | Lab | 68,502 | 71,586 | 3,084 | 4.50 |
West Ham | Lab | 83,345 | 86,902 | 3,557 | 4.27 |
Sittingbourne & Sheppey | Con | 72,615 | 75,638 | 3,023 | 4.16 |
Cities of London & Westminster | Con | 55,921 | 58,071 | 2,150 | 3.84 |
Colchester | Con | 69,819 | 72,295 | 2,476 | 3.55 |
Ealing Central & Acton | Lab | 68,374 | 70,798 | 2,424 | 3.55 |
Nottingham East | Lab | 55,250 | 57,132 | 1,882 | 3.41 |
Bedford | Con | 67,998 | 70,259 | 2,261 | 3.33 |
South Northamptonshire | Con | 81,801 | 84,427 | 2,626 | 3.21 |
Cheltenham | Con | 74,891 | 77,222 | 2,331 | 3.11 |
City of Durham | Lab | 64,614 | 66,618 | 2,004 | 3.10 |
Leicester South | Lab | 70,055 | 72,227 | 2,172 | 3.10 |
Stroud | Con | 78,539 | 80,909 | 2,370 | 3.02 |
Top 20 losers in percentage terms
Constituency | Party | 1st Dec 2014 | 1st Dec 2015 | Change | Change % | |
111 | Canterbury | Con | 78,850 | 68,695 | -10,155 | -12.88 |
296 | Ilford South | Lab | 88,135 | 78,212 | -9,923 | -11.26 |
367 | Middlesbrough | Lab | 64,144 | 57,532 | -6,612 | -10.31 |
109 | Cambridge | Lab | 74,665 | 67,266 | -7,399 | -9.91 |
503 | Slough | Lab | 83,990 | 76,668 | -7,322 | -8.72 |
241 | Glasgow North East | SNP | 65,607 | 60,671 | -4,936 | -7.52 |
10 | Amber Valley | Con | 69,532 | 64,454 | -5,078 | -7.30 |
273 | Hayes & Harlington | Lab | 75,090 | 69,700 | -5,390 | -7.18 |
647 | Yeovil | Con | 82,157 | 76,351 | -5,806 | -7.07 |
405 | North East Fife | SNP | 60,899 | 56,716 | -4,183 | -6.87 |
295 | Ilford North | Lab | 72,947 | 67,980 | -4,967 | -6.81 |
205 | Edinburgh East | SNP | 64,862 | 60,452 | -4,410 | -6.80 |
54 | Birmingham, Selly Oak | Lab | 73,353 | 68,460 | -4,893 | -6.67 |
597 | Wansbeck | Lab | 63,026 | 58,883 | -4,143 | -6.57 |
3 | Aberdeen North | SNP | 66,652 | 62,280 | -4,372 | -6.56 |
206 | Edinburgh North & Leith | SNP | 78,026 | 72,954 | -5,072 | -6.50 |
116 | Carlisle | Con | 64,673 | 60,507 | -4,166 | -6.44 |
396 | North Ayrshire & Arran | SNP | 75,471 | 70,779 | -4,692 | -6.22 |
453 | Portsmouth South | Con | 68,792 | 64,577 | -4,215 | -6.13 |
63 | Blyth Valley | Lab | 63,712 | 59,819 | -3,893 | -6.11 |