I'm not sure Derry was ever 75 per cent Catholic in the pre-Commission days, ard mhacha (14,300 catholic voters in 1966; 9,235 protestant). Still quite a gerrymandering achievement that it was able to return 12 protestant councillors and eight catholic. Other examples include Co Fermanagh, which was a 50-50 split, more or less, but with unionists outnumbering catholics 2-1 on the council and in Westminster representation. (Fermanagh county council employed 370 people of which 350 were protestant.)

Dungannon was 53 per cent catholic but council representation was 14-7 in favour of protestants. Kilkeel was 60 per cent catholic (you'd never believe it to see the town centre now!) but under unionist control from 1937 onwards.

Shirley Porter is as odious an individual as you could shake a stick at, but was a mere novice at gerrymandering. (For one thing, she got caught in the act.)